آموزشی: مقاله :زبان اصلی هارد دیسک و اجزای آن و قطعات و چگونگی ارتباط آن ها

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Have you ever wanted to see what the inside of your hard drive looks like? From the outside it may look like a small, simple box-shaped device, but there is an immense amount of technology inside. Read through our article which details the internal components of a modern hard drive to get a better understanding of how your data is stored, and recovered.
In order to make this information more relevant we will use a new 1TB Western Digital 3.5″ hard drive, a WD10EARX.
The main enclosure, usually black in colour, is what the everyday computer user will know to be the hard drive. This is called the hard disk assembly, or HDA. The top side of the HDA is covered by the top cover, usually silver in colour, with a sticker detailing information about the hard drive such as manufacturer, capacity, model, serial number etc.


The underside of the hard drive houses the printed circuit board, or PCB. This is the green electronic board which covers about half of the underside of the drive. The components of the PCB are usually on the inner side of the PCB, protecting them from damage. Some manufacturers, such as Samsung, place the components on the outer side of the PCB where they can be easily damaged. In this Western Digital example, the components are safely on the reverse side of the PCB. The base of the motor spindle is also shown. This contains a bearing around which the platter/s can spin inside the HDA.

SATA drives have 2 connectors. The small connector carries data to and from the drive, whilst the larger is the power connector for 5v and 12v lines.















When removed from the hard drive, the underside of the PCB reveals the working components. There are 3 main components of the PCB. They are the main controller unit, or MCU; motor controller and onboard memory (cache). The MCU is equivalent to the processor (CPU) of your computer, essentially the brains and computing power of the drive. The motor controller performs the function of spinning up the platter/s inside the drive, and controlling the movement of the voice coil which directs head movement. The memory chip is like the RAM in your computer. It is labelled as ‘cache’ in the hard drive world and stores data being written to, or read from, the drive. The contacts for the heads and motor can also be seen. The ROM information is also found on the PCB. Sometimes this is found on an 8-pin IC (chip), other times this information is stored in the MCU itself. In this example the ROM is stored on the 8-pin IC above the onboard memory. The ROM contains a portion of the firmware required to start the drive up, whilst the rest of the firmware is read from the drive platter itself.

The underside of the lid houses a seal which protects the drive from the outside world. The top lid is usually secured by T8 screws, or T6 in the case of 2.5″ laptop drives. Opening a hard drive in any environment other than a certified clean room will contaminate the drive’s internals and spell disaster.

Here we have the inside of the HDA. This view shows the main components of the drive. The platter, or platters, store your data. They are usually made from aluminium or glass and are covered in several layers of other materials. The platters will spin anywhere between 5,400 RPM to 7,200 RPM in average consumer hard drives. The head stack assembly, or HSA, is the assembly which holds the read and write heads. These heads fly nanometers over the surface of the drive on sliders, reading and writing your data. The magnets allow the voice coil to function, allowing the HSA to move and is complemented by a bottom magnet below it. A plastic adapter holds the heads contact in place, making contact with the PCB on the other side. An internal air filter collects any contamination that might reside in the drive such as oil or metallic fragments, all on a micro scale. A plastic ramp is included to hold the heads in place whilst the drive is not in use. Some drives park the heads in the middle of the platters on a special layer, this being seen mainly on older drives.

The air filter purifies the air circulating in the drive whilst in operation. It will collect any microscopic fragments of metal or oil which are used in the manufacturing process, or created through wear and tear. A hard drive which has suffered a head crash will have a filter tainted with dark material and appear black or grey. This dark material being the particles of platter/s and head slider/s.

With the top magnet removed, the voicecoil and bottom magnet are visible. The concept of this is the same as the driver in a speaker system, allowing quick and precise movements in either direction. The magnets are neodymium, the strongest form of permanent magnets being able to hold 1,000 times their weight. A stopper, or limiter, is placed at each end of the voicecoil to limit its range of movement. The bearing on which the HSA moves is also shown.

A plastic connector is used to hold the contacts for the heads in place. They make contact with the relavant pads on the PCB on the other side.

The heads connector has a rubber seal to prevent any contaminants from entering the HDA.

The HSA holds the actual read and write heads at the end of the assembly, fixed to sliders. This particular drive has 6 heads, 3 pairs of 2. For each side of the platter there is one read and write head.

The sliders allow the head assembly to fly over the platters, only a few nanometers above the surface. This is many times thinner than the thickness of a human hair. When the drive is spinning at full speed, the heads will be unloaded from the parking ramp and fly over the platters. The air passing under the sliders at this speed is enough to lift them above the surface of the platters.
The rectangular black objects on the end of HSA are the sliders, whilst the actual read/write head elements themselves are so small they are hard to see without a microscope.

The read and write heads work with very weak signals. For these signals, the “ones and zeros​

 

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[h=1]Hard disk drive read channels " a must for perpendicular recording[/h]

The electronic heart of a hard disk drive is the read-channel integrated circuit (IC). Over the years, read-channel designers have delivered dramatic improvements in signal-to-noise ratio (SNR), enabling accurate, reliable recovery of user data from noisy analog signals. Hard drive designers have taken advantage of SNR improvements to make data tracks on a storage disk smaller and pack those tracks tighter. Today this enables areal densities of up to 80-gigabytes-per-platter in desktop-level drives (3.5-inch platters), 40-gigabytes-per-platter in mobile drives (2.5-inch platters) and increased capacity in small-form-factor consumer device drives (1-inch and smaller). Data recorded on magnetic disk platters in a drive follow a complex analog path from being initially "read" to final digitization in a read-channel. This article focuses on the process required to ensure the data's accuracy along this path while accommodating the need for ever-increasing storage capacity.​

Figure 1. Total HDD capacity increase over time by drive form factor.
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Figure 1 shows the continued growth in HDD capacities across several storage segments, including desktop, mobile and portable consumer. The form factors are based on the diameter of the disk in the disk enclosure. Over the last decade, total drive capacity (which accounts for drives that incorporate multiple platters) in a given form factor has increased as measured on a log scale not just a linear scale. Increased disk diameter and rotational velocity of the application for a given areal density technology require increased channel speed. Decreased disk diameter and rotational velocity tend to focus on the channel's low power capability. Higher channel frequency requirements have grown with the areal density increases for a given form factor and type of drive product. Consumer and small diameter form factor drives have a slower frequency, but in that sub market the focus is on power saving capability for portable low-power usage drives. These one-inch and sub-one-inch drives are emerging as the storage medium of choice for portable devices requiring high capacity, including digital cameras and camcorders, MP3 players, mobile phones. Perpendicular recording for increased disk areal densities​

The feature-rich analog front end of a read channel integrates multiple technologies in a single design used for horizontal (also known as longitudinal) recording techniques. However, channel design is now being further enhanced to enable higher capacity perpendicular recording. Perpendicular recording techniques will help meet the torrid capacity increases seen on disk drives through increased areal densities ranging from 100 to 300 gigabits-per-square-inch. The waveforms and data path described here depict signals enabled using perpendicular recording. Popular representation of a perpendicular signal is that of a hyperbolic tangent transition model such as used in publications by Bertram, et al at UCSD. As shown in Figure 2, the perpendicular isolated pulse model is asymmetric where the horizontal pulse basic model shape is symmetric with even symmetry. A sector is written with a preamble, sync mark and data. The preamble is constant frequency and the sync mark is a fixed pattern. The customer's data is scrambled with a pseudo-random sequence, encoded, protected with an optional added low density parity in block code and pre compensated before being written on the disk as NRZ data, known as non return to zero. Servo patterns which are used to position the head on the data track have a similar structure of preamble, SAM (servo address mark), and Gray code with additional, bursts and a repeatable run out field.​

Figure 2. Comparison of basic perpendicular and horizontal signal transition.
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Following the data path​

"Reading" a signal in a hard disk drive begins at the media (the drive's storage platter) and head transducer. The head transducer is located prior to the preamp in the data path (see Figure 3). The head transducer output is driven from magnetic data pattern previously written on a rotating disk.​

Figure 3: HDD diagram showing pre-amp and read-channel IC locations.
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The data is organized into sectors containing a preamble of a constant frequency to synchronize the data detection before a sync mark. This applies whether the read signal is from a traditional horizontal recording or perpendicular recording. The simulated data field at the change from preamble to sync mark and data is seen in the signal as shown in Figure 4. This is an ideal head transducer signal without any noise representing the read of perpendicular media. The sync mark followed by data begins at the end of the constant frequency preamble signal. The resolution difference is evident between the amplitude of the higher constant frequency preamble to the left of the capture (bit cells 0 through 20) and the subsequent lower frequency random amplitude of the sync mark and data signals on the right side of the figure (cells 20 through 100). As discussed earlier, a key feature of a perpendicular signal at lower density is that more time is spent at the signal maximum or minimum amplitude (such as the maximum seen at bit cells 85-90).​

Figure 4. Ideal perpendicular magnetic signal output from the head transducer before the preamp.
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Figure 5 shows a series of constant frequency transitions, represented magnetically on the right and with the resulting signal from the read sensor on the left. The signals have overemphasized asymmetry. The arrows in the recording layer of the disk's surface represent the magnetically written data from the write element of the recording head. The read sensor senses the magnetization in the recording layer of the disk and produces the signal shown as the disk media rotates below the read sensor. The signal is dependent on whether the recording media is designed to emphasize horizontal or perpendicular recorded transitions.​

Figure 5: Cross sections of perpendicular and horizontal media transitions with overemphasized signal asymmetry.
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Preamp​

Following the head transducer, a signal travels to the HDD preamplifier IC, which provides gain for the signal output as well as biasing for the head's magnetic sensor. The bias allows better reproduction of the signal's magnetic transitions. The signal, therefore, is amplified by the preamp to significantly higher amplitude to meet the tens of millivolts required to preserve the signal-to-noise (SNR) level capability of the head signal and maximize the read-channel's capabilities once it arrives at the channel. In addition, the output of the preamplifier is differential to allow any noise pick-up to be common mode on both preamplifier differential signal lines between the preamplifier " located on suspension out by the head -- and the read-channel on the drive card. The preamp differential signals travel down the suspension on flex circuit traces to a pressure connection, which transitions the signal to the drive card trace. Given prudent drive board and flex circuit layout, with attention to impedance matching and ground returns, any noise pickup should be small -- compared to the signal " and easily handled by the common mode rejection of the channel's analog front end.​

Figure 6: Stages in a read-channel analog front-end.
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The Read-Channel​

The channel can be a single chip or integrated as part of a storage system-on-a-chip (SoC). For this discussion, the channel refers to the core that is used in either application. A channel's chief function is to convert the analog signal presented at the input back into the digital data that has been stored on the disk. AC coupling​

The first stage of the analog front end of the channel core consists of a stage to remove DC offset in the signal. This is accomplished through AC coupling and DC baseline correction. Due to the lower frequency content of the perpendicular signal and codes, the AC coupling corner frequency is lower than for horizontal recording. As seen in Figure 7, the signal amplitude is adjusted vertically by the AC coupling, and DC differential signal offset is attenuated. The remaining positive DC offset shift (toward +0.04 in the preamble and subsequent sync mark and data field) is compensated later in the summing junction.​

Figure 7. Perpendicular signal after AC coupling still showing some DC offset of positive versus negative peaks in the preamble.
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VGA​

The variable gain amplifier (VGA) provides gain determined by the automatic gain control loop. The main function is to control signal level for optimum performance in the analog-to-digital (ADC) converter block. Too much gain can cause the ADC sample values to rail at maximum or minimum ADC levels; too little gain can cause quantization noise to dominate SNR and adversely affect bit error rate performance. Summing Junction (Σ)​

This stage adds in any additional DC correction necessary beyond the DC attenuation provided in the AC coupling stage. The goal of the perpendicular waveform DC correction is the same for horizontal recording at this stage: to keep the signal centered on the baseline which will become mid scale for the ADC converter so that the sequence detector trellises will work optimally to determine the sequence bits from the samples presented. This also keeps signal offsets from driving the signal amplitude into saturation. So correction reduces the preamble offset (seen in Figure 7), producing a more centered signal in Figure 8.​

Figure 8. Perpendicular signal after DC offset and MRA correction.
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MR Asymmetry​

MR asymmetry (MRA) correction and the continuous time filter (CTF) work to linearize the signal prior to the analog to digital converter (ADC). MRA correction works to reconstruct linearity that may have been lost in the head transducer stage during the conversion of the magnetic signal on the disk to an electrical signal at the output of the head. The biasing of the head signal is adjusted to keep the signal in the linear range of the head sensitivity curve. However, if the magnetic signal amplitude changes due to fly height or disk magnetic variation exceeds the head transducer linear range, saturation in the peak or trough of the electrical head signal can occur. The MRA correction uses signal offset to determine the amount of squared signal to add back to restore the positive and negative symmetry of the signal (Figure 8). Continuous Time Filter​

The continuous time filter (CTF), applied after the MR asymmetry correction, provides mid-band peaking to help with achieving the target signal response and keeps the signal energy below the Nyquist rate to minimize any aliases that may occur when the analog signal is converted to a sampled representation. While aliases may not have a large effect on a drive surface's bit error rate performance, they can cause an impact to HDD manufacturing yields. The CTF is typically a multiple pole low pass filter with a zero available for mid-band peaking. Signal peaking is used to emphasize frequency components, which are useful in shaping the signal to meet the digital target signal characteristic. The mid-band peaked signal as seen in Figure 9 is optimally target- matched in the finite impulse response (FIR) filter, resulting in the signal shown later in Figure 11.​

Figure 9. Perpendicular signal after CTF low pass filter.
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A to D converter block​

The analog to digital converter block (ADC), also known as a flash, converts an analog signal to digital samples quantized in time and amplitude. The clock used is the output of a digital phase-locked loop, which tracks the channel rate clock frequency. The output of the ADC is used as feedback to control the timing of the digital phase-locked loop as well as the automatic gain control, DC baseline correction, and FIR adaptation.​

Figure 10. Sampled signal after ADC, analog to digital converter.
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Digital FIR​

The finite impulse response (FIR) filter performs filtering to match signal characteristic to the ideal target response for bit detection. As with all sections of the analog front end, the performance of this filter is important to achieve the desired architectural target response. While the function of filtering is consistent with horizontal recording designs, the optimal targets for perpendicular waveforms have changed so the allowable tap gain ranges have been adjusted to help filter the waveform to match the target. Evidence of the FIR adaptation in Figure 11 is that the preamble signal amplitude approaches the amplitude of the sync mark and data envelope. In addition, FIR delay can be seen from the end of preamble in Figure 10 (bit cell 23) to that same point post-FIR in Figure 11 (bit cell 33). Care is exercised in the design of the FIR to avoid distortion and any degradation of the signal.​

Figure 11. Perpendicular signal after FIR, finite impulse response filter.
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Digital Read Data Waveform​

At the output of the analog front end, the signal is now in a fully digital form ready for detection. Regardless of whether the data was recorded using perpendicular or horizontal techniques, the read channel analog front-end functions are similar. The sample stream is submitted to the sequence detector to begin decoding in trellises for bit recovery. Once bit recovery is completed, parity post processing can then be performed, followed by decoding the run length limited codes and de-scrambling the resulting sequence. These steps ultimately reveal the original user data. The ability of a hard disk drive to continually deliver higher capacity storage has been driven by a stream of innovations over the past dozen years, such as the switch from thin film heads to magneto resistive (MR) to giant MR heads, and the transition from peak-detect-based read channels to PRML. Implementation of perpendicular recording represents the next major shift in HDD component technology, and read-channels optimized for both horizontal and perpendicular recording modes will provide the superior signal processing performance needed to address current and future capacity points. Hard disk drive read channels " a must for perpendicular recording | EE Times


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[h=1]How Hard Disk works[/h]

Have you ever given it a thought what happens when you double click on an icon of application or some file. During the course of time this operation is performed, you might see flickering of light associated with hard disk and listen to churning sound of hard disk. This definitely means that something is going on inside, rather one might correctly guess that data is being accessed.


To understand this first we need to understand, what is hard disk, how it stores data and how does it access the data.
History
The hard disks track their origin with IBM 305 computer during the year 1955. The hard disk started as large

disks up to 20 inches in diameter holding just a few megabytes of memory. During the starting years they were called "fixed disks" or "Winchesters" (a code name which was generally used for a popular IBM product). They later became known as "hard disks" so as to distinguish them from "floppy disks." As the 1980s began, hard disk drives were a rare and very expensive and were very rare on personal computers (PCs); however by the late '80s, hard disk drives were standard on all Personal Computers.


Hardware-Physical Components
A hard disk contains a set of electromagnetic platters (consider it as a plate with fixed size hole at centre of them or CDs) stacked on top of one another (a bit like many CDs in a stack) with a narrow gap between each platter. These platters typically spin at 3,600 or 7,200 rpm when the disk is operating. Each platter is usually double-sided i.e. each platter has 2 sides to store data, and each side has its own read/write head. So, if you've got 4 platters, you've probably got 8 heads.

Each platter has set of concentric rings (technically called a "track") which are used to store the data and each head reads from one of these concentric rings on the cylinder. There can be more than a thousand tracks on a 3.5-inch hard disk. All the heads move at the same time and are positioned to read or write to the same track on their respective platter, which means that they form a cylindrical shape and hence are known as cylinder. So, if head 2 is positioned to read from track 23, head 3 will also be positioned to read from track 23. Therefore, we might say that head 2 is positioned to read from cylinder 23 (which implies that head 3 and further heads are also positioned to read from same track i.e. cylinder 23).

Finally, each track is split into small segments. Each segment is called a "sector", as shown in the figure. A sector is the smallest physical storage unit on a disk, and is most of the time 512 bytes (0.5 kB) in size. All the hardware operations take place in terms of sectors.

If some application or some file wants to access one particular sector, then it could refer it by specifying which head it is on, and which cylinder it is on and finally the appropriate corresponding sector. That would then uniquely identify the sector that we wanted to access.

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- In many instances from component failure to corrosion to faulty construction methods a PCB would fail leaving you scratching your head on what to do to recover your data. Many people purchase identical hard drives on eBay in the hopes that they can simply replace the PCB and all will be good in the world, but unfortunately this is NOT the case.



- Firmware is important and is unique to the drive! In most cases part numbers will not assist you in matching this.


Example:
- If you were to buy two new identical hard drives and decided to exchange the printed circuit boards over to each other, the chances of the drives still functioning correctly is probably in the high 90's.


- But if you were to attempt this same procedure six months after normal operation, the chance of the drives working would drop to 5% and lower!


- The reason being that during a hard drive operation it will relocate sectors with degrading read times, this extends the life of a hard drive with automatic relocation of slow sectors. Unfortunately, this information alters firmware making the PCB unique to that drive , so it is imperative during PCB failure to physically remove this chip containing this unique firmware to a functioning matching PCB. In short, you can match the printed circuit board by model, family and country but firmware will need to be transferred and/or read and written to the new donor parts.


- Is when you replace the unique components from a failed hard drives printed circuit board to a matching replacement PCB or replace the failed component on the original PCB

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First step in do it yourself hard drive

PCB Repair

 

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The goal of this article is to show you how a modern Hard Disk Drive or HDD built. What are its main parts, how do they look and what are these parts names and abbreviations. As an example we are going to disassemble 3.5" SATA drive.
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To make it more fun we going to tear to pieces pretty new 1TB Seagate ST31000333AS drive. Let's take a look on our "Guinea pig".​

The fancy piece of green woven glass and copper with SATA and power connectors called Printed Circuit Board or PCB. PCB holds on place and wires electronic components of HDD. The black painted aluminum case with all stuff inside called Head and Disk Assembly or HDA. The case itself called Base.​

Now let's remove PCB and see electronic components on the other side.​

The heart of PCB is the biggest chip in the middle called Micro Controller Unit or MCU. On modern HDDs MCU usually consists of Central Processor Unit or CPU which makes all calculations and Read/Write channel - special unit which converts analog signals from heads into digital information during read process and encodes digital information into analog signals when drive needs to write. MCU also has IO ports to control everything on PCB and transmit data through SATA interface.​

The Memory chip is DDR SDRAM memory type chip. Size of the memory defines size of the cache of HDD. This PCB has Samsung 32MB DDR memory chip which theoretically means HDD has 32MB cache (and you can find such information in data sheet on this HDD) but it's not quite true. Because memory logically divided on buffer or cache memory and firmware memory. CPU eats some memory to store some firmware modules and as far as we know only Hitachi/IBM drives show real cache size in data sheets for the other drives you can just guess how big is the real cache size.​

Next chip is Voice Coil Motor controller or VCM controller. This fellow is the most power consumption chip on PCB. It controls spindle motor rotation and heads movements. The core of VCM controller can stand working temperature of 100C/212F.​

Flash chip stores part of the drive's firmware. When you apply power on a drive, MCU chip reads content of the flash chip into the memory and starts the code. Without such code drive wouldn't even spin up. Sometimes there is no flash chip on PCB that means content of the flash located inside MCU.​

Shock sensor can detect excessive shock applied on a drive and send signal to VCM controller. VCM controller immediately parks heads and sometimes spins down the drive. It theoretically should protect the driver from further damage but practically it doesn't, so don't drop you drive - it wouldn't survive. On some drives shock sensors used for detection even light vibrations and signals from such sensors help VCM controller tune up heads movements. Such drives should have at least two shock sensors.​

Another protection device called Transient Voltage Suppression diode or TVS diode. It protects PCB from power surges from external power supply. When TVS diode detects power surge it fries itself and creates short circuit between power connector and ground. There are two TVS diodes on this PCB for 5V and 12V protection.​

Let's take a quick look on HDA​

You can see motor and heads contacts which were hiding under the PCB. There is also small almost unnoticeable hole on HDA. This hole called Breath hole. You maybe heard old rumor which says that HDD has vacuum inside, well that is not true. HDD uses Breath hole to equalize pressure inside and outside HDA. From the inside Breath hole closed by Breath filter to make air clean and dry.​

Now it is time to take a look under the hood. We are going to remove the drive's lid.​

The lid itself is nothing interesting. Just a piece of steel with rubber cord for dust protection. Finally we are going to see HDA from inside.​

Precious information stored on platters, you can see top platter on the picture. Platters made of polished aluminum or glass and covered with several layers of different compounds including ferromagnetic layer which actually stores all the data. As you can see part of the platter covered with the Dumper. Dumpers sometimes called as Separators located between platters, they reduce air fluctuations and acoustic noise. Usually dumpers made of aluminum or plastic. Aluminum dumpers better for cooling air inside HDA.​

Next picture shows platters and dumpers from the side​

Heads mounted on Head Stack Assembly or HSA. This drive has parking area closer to the spindle and if power is not applied on a drive, HSA normally parked like on the picture.​

HDD is a precision mechanism and in order to work it requires very clean air inside. During work HDD may create some very small particles of metal and oil inside. To clean air immediately a drive uses Recirculation filter. This hi-tech filter permanently collects and absorbs even finest particles. The filter located on the way of air motion created by platters rotation.​

Now we are going to remove top magnet to see what is under.​

HDDs use very strong Neodymium magnets. Such a magnet is so strong it could lift up to 1300 times its own weight, so don't put your fingers between magnet and steel or another magnet - it can develop great impact. You can see on this picture there is a HSA stopper on the magnet. HSA stoppers limit HSA movements, so heads wouldn't bang on the platters clamp and on the other side they wouldn't just fly off the platters. HSA stoppers may have different construction but there are always two of them and they always present on modern HDDs. On this drive the second HSA stopper located on HDA under the top magnet.​

And here is what you may see under the top magnet.​

There is the other HSA stopper. And you also can the second magnet. The Voice coil is a part of HSA, Voice coil and the magnets form Voice Coil Motor or VCM. VCM and HSA form the Actuator - a device which moves the heads. Tricky black plastic thingy called Actuator latch is a protection device - it will release HSA when drive un-parking (loading) heads normally and it should block HSA movements in the moment of impact if drive was dropped. Basically it protects (should, at least) heads from unwanted movements when HSA is in parking area.​

On the next step we going to take out HSA​

HSA has precision bearing to make movements nice and smooth. The biggest part of HSA milled from piece of aluminum called the Arm. Heads Gimbal Assembly or HGA attached to the Arm. HGAs and Arms usually produced on different factories. Flexible orange widget called Flexible Printed Circuit or FPC joins HSA and plate with heads contacts.​

Let's take closer look on each part of HSA.​

Voice coil connected to FPC​

Here is the bearing​

On the next picture you can see HSA contacts​

The gasket makes connection airtight. The only way for air to go inside HDA is through the breathing hole. On this drive contacts covered with thin layer of gold, for better conductivity.​

This is the classic definition of the arm. Sometimes by the arm imply the whole metal piece of HSA.​

The black small things at the end of HGAs called Sliders. In many sources you can find that sliders claimed as actual heads but a slider itself is not a head it's a wing which helps read and write elements fly under the platter's surface. Heads flying height on modern HDDs is about 5-10 nanometers. For example: an average human's hair is about 25000 nanometers in diameter. If any particle goes under the slider it could immediately overheat (because of friction) the heads and kill them that's why clean air inside HDA is so important. The actual read and write elements located at the end of the slider and they are so small that can only be seen under a good microscope.​

As you can see slider's surface is not flat, it has aerodynamical grooves. These grooves help a slider fly on the certain height. Air under the slider forms Air Bearing Surface or ABS. ABS makes slider fly almost parallel to the platter's surface.​

Here is another picture of the slider​

You can clearly see heads contacts.​

There is very important part of HSA which we haven't discussed yet. It called the preamplifier or preamp. The preamp is a chip, which controls heads and amplifies signals from/to them.​

The reason why the preamp located inside HDA is simple - signals from heads are very weak and on modern HDDs have more than 1GHz frequency, if take the preamp out of HDA such weak signals wouldn't survive, they will disappear on the way to PCB.​

The preamp has much more tracks going to the heads (right side) than to the HDA (left side), it's because HDD can work only with one "head" (pair of read an write elements) at a time. HDD sends control signals to the preamp and the preamp selects the head which HDD needs at the current moment. This HDD has six contacts per "head", why so many? One contact is for ground, other two for read and write elements. Other two for microactuators - special piezoelectric or magnetic devices which can move or rotate slider, it helps tune up heads position under a track. And finally the last contact is for a heater. The heater can help adjust heads flying height. The heater can heat the gimbal - special joint which connects slider to HGA, the gimbal made from two stripes of different alloys with different thermal expansion. Once gimbal got heated it bents itself toward platter's surface and this action reduces flying height. After cooling down the gimbal straights itself.​

Enough about heads, let's continue disassembling. We going to remove top dumper.​

That's how it looks​

And next picture shows HDA without the top dumper and HSA​

Now the top platter is not covered, you also can see the bottom magnet​

Let's move further and remove the platters clamp​

The platters clamp squeezing platters into the platters packet, so they wouldn't move.​

Platters sitting on the spindle hub, the platters clamp creates enough friction to hold platters on the hub when spindle rotates.​

Now when nothing holding platters on the hub we are going to remove the top platter and next picture shows what we may see under.​

Now you see how platters packet has room for heads - platters laying on spacer rings. You can see the second platter and the second dumper.​

The spacer ring is a precision detail made of non-magnetic alloy or polymer. Let's take it out.​

Finally we are going to shake out the rest of the stuff from HDA and see the base​

That's how the breath filter looks. And the breath hole located right under the breath filter. Let's see the breath filter closer.​

Because air from outside definitely has dust the breath filter has several layers of filtration and it's much thicker than recirculation filter, it also may have some silica gel inside to reduce air moisture.​

I hope you found something interesting in this article. You can discuss this article on our forum.​

If you have questions about this article you can contact us by e-mail: hddscan@gmail.com​

This article has been written exclusively for HDDScan​

 

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[h=2]Hard-drive (HDD) WD3200AZDX has stopped working[/h]

This happens when you install PC ATX power source unit with modular plugs and use cables from other unit from the other company. Power voltages will mix up of course as it happend in this case. When you switch on your PC, after few seconds some smoke are coming from PC case. Something wrong has just happened. Yes of course, you have mixed cables and power source and this is result. What was wrong? There are companies in the world which do different cables for their modular PC ATX power sources. So you have just sourced 12V voltage to 5V because of modular cables are not compatible. And it killed your HDD with precious data on it. This happened to my friends. And story is about how to recover data from dead hard-drive.​

Figure 1: HDD WD3200AZDX patient without life.​

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Patient is HDD WD3200AZDX with capacity 320GB, 5200RPM, 32MB cache and SATA interface. It is green HDD from Western Digital. You can see it on figure 1.​

Figure 2: dismounted PCB board from HDD - top.​

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Figure 3: dismounted PCB board from HDD - bottom.​

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I dismounted PCB board from dead HDD and at first look it is clear that one chip on the board is totally burned-out. It seems that it is HDD motor driver integrated circuit. Situation is visible on figure 2 and 3. Now what? HDD contains precious data so I should take this to data recovery professionals. I am sure that they recover data from unopened HDD, but at what price? Is it worth? If you have there very precious data for example your company's data which worth thousands, YES, YOU SHOULD TAKE HDD TO DATA RECOVERY PROFESSIONALS. But if you have some private precious data or you can’t afford professionals then you should consider data recovery in DIY way and continue reading this article. At first you should know that in this case, it is not easy way to recover your data. I have tried it and finally done it, but it took me a lot of time. So I want to share my experiences in this area.​

​

[h=2]How to recover data[/h]

My first idea was replacing the burned PCB board and taking new one from exactly the same functional HDD model of course. I knew that if you have exactly the same HDD then it is easy, because you can use spare parts from functional one. But I wasn't lucky because PC shops didn't sell this model of HDD any more. Then I tried eBay and other e-shops but with no luck. It was time to try something else. I decided to buy only PCB board. I haven't enough information where get I this spare PCB board for HDD from. So I tried to google it. And I was lucky, I found company which sell these PCB boards for HDDs. Here is link HDD-parts. Specifically this PCB was my needed board. How do you know which one do you need? On PCB board is number which identify PCB board of your HDD. You can see it on figure 4.​

​

Figure 4: PCB board number.​

​

The new PCB board arrived and this was first try to fix this dead HDD and finally try to recover data from it. But there is one catch, every HDD has firmware and unique data stored on EEPROM or Flash memory on its PCB, see U12 IC on figure 5. Without this ROM chip you can forget to recover any data. Every HDD has different data stored on this ROM chip. It is unlikely that two the exact the same HDDs will work if you swap only PCBs between them. You need to swap chips from old board to new one too. But don't worry if you have some soldering skills then it is not such problem to do so. I used gas heated smd solder iron and tweezers. But don't forget to earth yourself at the beginning of process because of static electricity on your hands. This PCB board contains sensitive parts, so you should be very careful.​

​

​

Figure 5: ROM chip with important firmware and unique data of HDD.​

​

The ROM chip is swapped as you can see on figure 6. The next step is mount this PCB board to HDD body. After that I could finally connect it to PC and try to recover important data. I was happy and excited at same time, because it should be my last step to recover data from HDD. Unfortunately it wasn't. When I connected "healed" HDD to PC and switch power on, it behaved strange. At first there was hope because BIOS detected drive. So clearly new PCB board and swapped ROM chip with firmware work. But OS didn't detect HDD and no recovery software did it at all. I searched new info about this situation with google and I found that I should listen to HDD if there is some strange steady clicking noise. I have no luck so far, so yes it was "click of death sound". Experts claim that it is caused by malfunctioned heads or pre-amp which amplifies signals from heads. So it make sense if 12V burned out integrated circuits which were supplied from 5V then it is possible that heads or pre-amp is burned too. But unfortunately this IC pre-amp is situated on the arm with heads inside of HDD. I decided to confirm these news with tracking down 5V copper track on PCB board. And once again yes the 5V power supply track clearly goes inside to source the pre-amp amplifier. It was crystal clear that pre-amp integrated circuit is dead.​

​

​

Figure 5: new PCB board with swapped ROM chip from old board.​

​

It took a lot of time to reach this stage. So I didn't give up and decided to continue. But it was risky. You can find a lot of posts on forums and videos on youtube that opening HDD can be one way ticket to destruct it forever. And in normal case it is true. First problem is dust, it is everywhere in air, although it is not visible. But it is dangerous for HDD platter and also heads. Second problem is certain torque when you unscrew and then screw cover back. There are some warning videos on youtube, why you should use torgue wrench (screw driver). After studying all these problems, I decided to take the risk and open HDD. But first things first, It was clear that I needed exact the same model of HDD which is WD3200AZDX. In that case I could be 100% sure that I can swap arm with head and pre-amp without any doubts. But as I mentioned before I wasn't lucky to buy one at first place, so I decided to find out if there is another model which has compatible heads with pre-amp. I read a lot of posts on forums (like this rml527.blogspot.sk) and finally I figured out that 320GB HDD contains the same platter that 500GB has. So for example if you have HDD with 1TB capacity most likely your HDD has 2 platters. Of course that information was very useful, because I knew that I have only one platter in this drive and also that 500GB drive has one platter too. After this research I find out that I should try to use WD5000AZDX (or WD5000AZRX). Once again I wasn't lucky so I couldn’t get or buy one WD5000AZDX. Then I decided to buy WD5000AZRX. There were more different details which I was worried about. Capacity was not 320GB as should be but 500GB, cache was 64MB but not 32MB as original HDD had. Even though I was convinced to do it. I wanted to give it one more try. So let's open HDD and let it over...​

​

​

Figure 6: WD5000AZRX HDD donor of arm with heads.​

​

Before you begin process of opening HDD you need to consider some facts and prepare some tools. Is it really worth to open the HDD? I don't want to convince you it is only your decision. I do not take any responsibility for damages and lost important data from your HDD. But if you decided to do so you certainly need good tools and the cleanest room and desk with low dust there as you are able to ensure. In my case for unscrewing I used TORX T8H bit and you can see it on figure 7.​

​

​

Figure 7: TORX T8H bit.​

​

I started with dead HDD for one reason. I have read that special "V" shaped tool is needed for proper arm with heads transplantation. And it is important to use it for arm with heads because it secures heads in distance between each other without contact. When you have only one platter HDD, then you have only two heads on arm. And they are opposite each other, one is for top and the other for bottom side of platter. Experts claim that if these heads are touching each other when you disassembling arm with heads from HDD body to other HDD, then it is highly likely that heads are damaged after end of process. So we need special tool which we can make from pill plastic cover. See figure 8.​

​

​

Figure 8: special "V" shaped tool.​

​

First goal was to get arm with heads from dead HDD. Please read this article from Gefund-IT (Datenrettung): Lassen Sie uns Ihre erste Wahl sein, Nicht Ihre letzte Hoffnung! Wir können Ihnen helfen! before you start unscrewing screws. I had prepared very clean desk in clean room. After that I started the process. At first I unscrewed all screws in circumference of the HDD's body. The last one was placed in bottom middle of body underneath adhesive label. Next I removed top cover from body and place it on desk upside down. Next step was to dismount connector from HDD's body which contains 2 screws. After that I dismounted cover piece which is above voice coil. Next I removed arm stopper lock with tweezers. This finall step allowed me to remove arm with heads from HDD's body. As soon as I removed arm with heads from HDD, I put top cover back to HDD's body to prevent dust contamination. All these steps you can see on figures 9, 10, 11, 12, 13, 14, 15, 16, 17.​

​

​

Figure 9: opened HDD WD3200AZDX.​

​

​

Figure 10: dismounting connector, first screw.​

​

​

Figure 11: dismounting connector, second screw.​

​

​

Figure 12: dismounting voice coil cover - first screw.​

​

​

Figure 13: dismounting voice coil cover - second screw.​

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Figure 14: final dismounting voice coil cover.​

​

​

Figure 15: after dismounting all screws.​

​

​

Figure 16: last step before removing arm with heads - dismounting arm stopper lock.​

​

​

Figure 17: faulty arm with heads removed from HDD's body.​

​

After removing faulty arm with heads from HDD, I was able to test my "V" shaped tool for heads protection on new arm from new HDD. This arm was dead enough and very good for this kind of training. So I cut strip from pill plastic cover and bended it to "V" shape. See figure 8. And I tested it on this faulty arm with two heads as you can see it on figure 18 and detailed on figure 19.​

​

​

Figure 18: test of "V" shaped tool on faulty arm with heads protected against touching each other.​

​

​

Figure 19: detailed view on "V" shaped tool for heads protection.​

​

So far so good, it seems that we found the way how to fix this dead HDD. After some playing and training with "V" shaped tool and arm with heads I gained confidence to do transplantation of fully functional arm with heads from new HDD to dead HDD. At first you need open next HDD which is donor in this case it is WD5000AZRX. The process was the same as dismounting dead HDD with the one exception, before you dismount arm stopper lock (see figure 16), you should put "V" shaped tool on arm to protect them against touching each other. See figures 20 and 21 how it should be. And after that you can carefully and gentle remove arm with heads from donor HDD's body and then put top cover back to HDD's body to protect against the dust from air. Its time to open dead HDD once again, but it is only top cover we need to dismount, because this HDD doesn't contain arm with head anymore. So now you can mount new arm with heads, but do it carefully and gentle. Take your time to do it right. As I did. When arm with heads is mounted on place where it should be and top head is above white plastic, put arm stopper lock back (see figure 16) to lock arm with heads against the accidental move. After that you can carefully and gentle remove "V" shaped tool from arm with heads so that both heads will land on white plastic holder. At the end of this process it should look like you see it on figure 15. Now it's time to put all parts together as they were at the beginning. But you should mount them in reverse order as you can see it from figure 10 to figure 14. I was lucky and did it how I described.​

​

​

Figure 20: "V" shaped tool used for heads protection.​

​

​

Figure 21: detailed view on "V" shaped tool used for heads protection.​

​

After all parts are on their places it is time to put cover back on HDD's body and to seal it with screws. From that point you should use screw driver with specific torque set on. But I don't own this special screw driver, so I took the risk and I did it according this guide. Finally dead HDD was sealed and it is time to test it. Before you connect it to PC with OS, first thing you should do, is to prepare another healthy HDD at least with the same or larger capacity than dead HDD has. The reason, why it is so important, is that you don't know how long this fix will last on dead HDD. So plan is simple, once dead HDD starts to work, you should copy all important data ASAP. In my case I had prepared new HDD with 1TB capacity and pre-installed OS. Now all is prepared to switch on PC and resurrect dead HDD. I switched on and HDD started to spin, so far so good. No strange sounds from it any more, no "click of death" sound. BIOS was able to detect HDD and OS started to boot. I had high hopes, finally OS booted and I ran file manager. OS finally detected HDD I was so happy. HDD was resurrected. I started to copy all important data from it. Finally I managed to recover all data from HDD. This experience learned me that sometimes it is worth to do crazy things. If you read all article you already know that I was forced to replace almost all important parts of HDD. At first it was burned PCB board and then arm with heads. It was not easy but finally I was lucky. I hope you will be lucky too and I also hope that this article can help you somehow.
​

 

[pese]

[h=2]The HDD Platter Capacity Database[/h]

​

This site shows which hard drive models currently on the market (or discontinued) use what platter density, how many platters and how many read/write heads.

These attributes are important for several reasons: larger platter density generally equals higher data throughput performance, but may result in slower seek performance. Meanwhile, less disks and actuator arms mean less moving parts in the drive to eventually break, and can also lower the heat and noise output of a drive. I research and collect data from online, as well as from drives that I manage to test in real life, and put it all in these lists for you folks to look at.

Anyway, choose which manufacturer made your drive:

​

• 
  [*=left]-Fujitsu
  [*=left]-Hitachi GST
  [*=left]-Samsung
  [*=left]-Seagate
  [*=left]-Toshiba
  [*=left]-Western Digital

​

​

Note: I try to keep the information updated and accurate, but I don't always get things right. Thenceforth comes a disclaimer: use of this database is at your own risk. For best results (and minimal heartache), please consult multiple sources other than just this site when searching for hard disk platter-related information.

A lot of the data on this site comes out of logical guessing; in other words, working out which platter density a given generation of drives uses, and using simple math to figure out the platter/head counts for specific capacities (rather than purchasing a bunch of drives and cracking them open). These lists were originally created because most of the drive makers don't release this info to the public anymore. (Some older company datasheets - such as those for Seagate's Momentus 5400.2 notebook drives - do list platter/head counts for each capacity. In those cases, I've provided their information in the lists for convenience.)

That said, if you see any drives/models that aren't listed or are listed incorrectly, feel free to sound off in either the comments form of the appropriate section or through the Contact form, and I'll see what I can do.

Posted by RML527 at 3:00 PM
Labels: Platter Capacity Database
​

 

[pese]

HDD Platter Database - Hitachi GST




Pick a drive width here. Notebook drives tend to be 2.5", while desktop models are 3.5".

-2.5" (Legacy: DK23xx Series)
-2.5" (Travelstar/Cinemastar/Endurastar)
-3.5"

HDD Platter Database - Hitachi - 2.5" (Legacy: DK23xx Series)




Here are all the models currently in the database for this manufacturer and drive width. Entries are sorted into sections based on platter density, and then manufacturer drive family.

Some tips:

Drives using odd sizes are sorted into whatever size category that's closest. For example, drives using 150GB platters are sorted into the 160GB/platter section, and drives using 200GB platters are sorted into the 250GB/platter section.​

​

The total capacity of the drive is shown beside each drive model.​

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A platter-head ratio is shown next to the total capacity tag in brackets. For example, a drive with a (1/2) ratio has one disk and two read/write heads. Drives that leave some amount of their platters unused in order to fit into a certain capacity (such as a 320GB drive based on a 500GB platter and two heads, which would have ~180GB space unusable) are marked as [short-stroked] next to the platter-head ratio accordingly.​

​

Any special features (increased rotational speed, interface types, unusual platter designs and stuff like that) are noted where necessary.​

​

This section was last updated on 09/02/2014.



6GB/platter Section (all drives under here use platters that can hold 6GB of data apiece.)

DK23AA (4200RPM, 512KB cache, ATA-66 interface)

DK23AA-60 6GB (1/2)​

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DK23AA-90 9GB (2/3)​

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DK23AA-12 12GB (2/4)​

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10GB/platter Section (all drives under here use platters that can hold 10GB of data apiece.)

DK23BA (4200RPM, 512KB [20GB: 2MB] cache, ATA-66 interface)

DK23BA-60 6GB (1/2 [short-stroked])​

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DK23BA-10 10GB (1/2)​

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DK23BA-20 20GB (2/4)​

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15GB/platter Section (all drives under here use platters that can hold 15GB of data apiece.)

DK23CA (4200RPM, 512KB [20 & 30GB: 2MB] cache, ATA-100 interface)

DK23CA-75 7.5GB (1/1)​

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DK23CA-10 10GB (1/2 [short-stroked])​

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DK23CA-15 15GB (1/2)​

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DK23CA-20 20GB (2/3 [short-stroked])​

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DK23CA-30 30GB (2/4)​

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20GB/platter Section (all drives under here use platters that can hold 20GB of data apiece.)

DK23DA (4200RPM, 2MB cache, ATA-100 interface)

DK23DA-10F 10GB (1/1)​

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DK23DA-20F 20GB (1/2)​

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DK23DA-30F 30GB (2/3)​

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DK23DA-40F 40GB (2/4)​

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DK23EB (5400RPM, 2MB cache, ATA-100 interface)

DK23EB-20 20GB (1/2)​

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DK23EB-40 40GB (2/4)​

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Endurastar N4K20/DK23FA-20N (4200RPM, 8MB cache, ATA-100 interface, Extreme Environment)

HTA422020F9ATN0/DK23FA-20N 20GB (1/2)​

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Endurastar J4K20/DK23FA-20J (4200RPM, 8MB cache, ATA-100 interface, Extreme Environment)

HTA422020F9ATJ0/DK23FA-20J 20GB (1/2)​

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30GB/platter Section (all drives under here use platters that can hold 30GB of data apiece.)

DK23EA (4200RPM, 2MB cache, ATA-100 interface)

DK23EA-20 20GB (1/2 [short-stroked])​

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DK23EA-30 30GB (1/2)​

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DK23EA-40 40GB (2/3 [short-stroked])​

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DK23EA-60 60GB (2/4)​

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DK23FB (5400RPM, 8MB cache, ATA-100 interface)

DK23FB-20 20GB (1/2 [short-stroked])​

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DK23FB-40 40GB (2/3 [short-stroked])​

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DK23FB-60 60GB (2/4)​

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40GB/platter Section (all drives under here use platters that can hold 40GB of data apiece.)

Travelstar 4K80/DK23FA (4200RPM, 2MB [60 & 80GB: 8MB) cache, ATA-100 interface)

HTS428030F9AT00/DK23FA-30 30GB (1/2 [short-stroked])​

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HTS428040F9AT00/DK23FA-40 40GB (1/2)​

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HTS428060F9AT00/DK23FA-60 60GB (2/3)​

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HTS428080F9AT00/DK23FA-80 80GB (2/4)​

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Note: these are Hitachi's last in-house notebook drives. After acquiring IBM's drive business, these were re-branded as the Travelstar 4K80 series, and subsequent Hitachi-branded drives (starting with the Travelstar 80GN and 5K80) were designed by IBM's Travelstar team.
​

​

 

[pese]

Micro miniature hard disk drive
EP 0560298 B1

Description

• [0001]
  The invention relates generally to computer systems and more specifically to hard disk drives with miniature disks of high storage capacity, e.g., one and eight tenths inch (1.8") diameter disks that store at least forty megabytes (40 MB).
  
• [0002]
  Huge numeric computer systems constructed during World War II were used to crack secret German military codes. With the advance of technology, the same computing power can now be placed in a handheld computer that sells at commodity prices. The advances in electronics and semiconductor technology that made this possible brought business computing to a personal level, e.g., in the IBM PC, Apple Macintosh, and other personal computer systems. Recently, personal computing has seen the introduction of the battery-powered portable computer, the so-called laptop computer, the still smaller notebook computer, and even a palmtop computer that is so small that it fits in a person's hand.
  
• [0003]
  While computers have been getting smaller in physical size, their memory and execution speeds have grown. To illustrate, one of the first operating systems for personal computers was called CP/M and marketed by Digital Research of Garden Grove, CA. The CP/M operating system ran on 64K bytes of main memory and used only one or two 250K byte eight-inch floppy disk drives. Today, certain laptop computer models, e.g., one by Apple Computer, Inc., require four megabytes of main memory and forty megabytes of built-in hard disk storage just to comfortably run Macintosh System-7 software system and a professional wordprocessor, e.g., Microsoft WORD.
  
• [0004]
  As a result of progressive innovation, hard and floppy disk drives have been migrating to smaller diameter disks. In 1980, the eight-inch hard disk standard drive was popular. More storage was later offered in the five-and-a-quarter-inch (5.25") mini-drives. And subsequently, new demands for still smaller disk drives produced the three-and-a-half-inch (3.5") standard drive.
  
• [0005]
  A typical micro-Winchester 3.5 inch drive is described in United States Patent 4,568,988, issued Feb. 4, 1986, to McGinlay, et al. This micro-Winchester was developed to provide the storage capacity and interface of a 5.25" mini-drive. This was possible because track densities of six hundred tracks per inch (TPI) were not a problem to the more advanced head positioning servo systems using voice coil motors (VCM) instead of stepper motor positioning. Specially plated hard disk media were required by micro-Winchester drives, so an industry of disk media suppliers evolved that offered 3.5 inch media as a standard inventory item. This prompted scores of other disk drive manufacturers to also base designs on the 3.5 inch format.
  
• [0006]
  The disk drive and media industry then settled on a two-and-a-half-inch (2.5") size for still further advances in micro miniaturization. This form factor allows a drive that has a length equal to the width of a 3.5 inch drive and a width one-half the length of a 3.5 inch drive. In other words, two 2.5 inch drives are capable of fitting within the space that a 3.5 inch drive typically requires. Drives of such size can be directly secured to printed circuit boards (PCBs), as opposed to the traditional panel and chassis mounting of standard sized drives. For example, the Apple Macintosh Powerbook 140 model 4/40, a laptop personal computer, uses a 2.5 inch forty megabyte hard disk drive similar to that described in United States Patent 5,025,335, issued June 18, 1991, to Stefansky. Closed-loop, embedded servo positioning systems are used, as well as head parking mechanisms to avoid having the heads slap against the data media areas while the laptop computer is being carried around and transported. Stefansky realized that further reductions in the size of disk drives would not be possible without redesigning certain components of the reduced size drive. The challenge in such invention lies in the reduction to practice, and not in the conception of a still smaller disk format. As Stefansky points out, the standard flexure used to mount heads on a load beam had to be changed to fit the smaller drives.
  
• [0007]
  A one-and-eight-tenths-inch (1.8") hard disk drive recently became available. For example, Integral Peripherals, Inc. (Boulder, Colorado) markets two models, a twenty megabyte (20 MB) MUSTANG 1820 and a forty megabyte (40 MB) STINGRAY 1842. The forty megabyte storage capacity model incorporates a dual platter 1.8 inch design. Published datasheets comment that the MUSTANG 1820 and STINGRAY 1842 models are designed for use in subnotebook, pen-based and palmtop computers. The 1.8 inch format is purported to be one half the size and weight of 2.5 inch drives. A ramp head loading device allows the drive to be spun down to remove the heads from harms way. A lock keeps the heads parked in a safe place. The stated advantage of this is that the drive spins up to speed in less than one second with the heads parked. The following Table I summarizes the specifications for the MUSTANG 1820 and STINGRAY 1842 as published by Integral Peripherals, Inc.

  		MUSTANG	STINGRAY
  Formatted Capacity	Per Drive	21.4 MB	42.5 MB
  Per Track	8704 Bytes	8704 Bytes
  Per Sector	512 Bytes	512 Bytes
  Sectors Per Track	17	17
  Functional	Recording Density (BPI)	46,100	46,100
  Flux Density (FCI)	34,600	34,500
  Area Density (MB/sq in)	89.5	89.5
  Disks	1	2
  Data Heads	2(4)	4(5)
  Data Cylinders	615	977
  Track Density (TPI)	1942	1942
  Recording Method	1,7 RLL Code	1,7 RLL Code
  Performance	Media transfer Rate	1.13 to 1.79	1.13 to 1.79
  	MB/sec	MB/sec
  Interface Transfer	Up to 4.0	Up to 4.0
  Rate	MB/sec	MB/sec
  Rotational Speed	3,571 RPM	3,571 RPM
  Latency	8.5 ms	8.5 ms
  Average Seek Time	< 20 ms	< 21 ms
  Track to Track Seek	8 ms	8 ms
  Time
  Maximum Seek Time	30 ms	30 ms
  Start Time (Typical)	1.5 sec	1.5 sec
  Buffer Size	32 Kbytes	32 Kbytes
  Interface	AT/XT	AT/XT
  Reliability	MTBF	100,000 hours	100,000 hours
  Start/Stops	1,000,000	1,000,000
  Unrecoverable Data	< 1 per 10[SUP]13[/SUP]	< 1 per 10[SUP]13[/SUP]
  Error Rate	bits read	bits read
  Power	5 VDC ±5% Startup	0.8 Amps	0.8 Amps
  Current
  Typical Power
  Dissipation
  Spin-up	3.5 watts	3.8 watts
  Idle	1.0 watts	1.1 watts
  Read/Write/Seek	2.0 watts	2.1 watts
  Power Savings	0.5 watts	0.6 watts
  Mode
  Standby Mode	0.035 watts	0.035 watts
  Sleep Mode	0.015 watts	0.015 watts
  Environmental	Temperature
  Operating	5°C to 55°C	5°C to 55°C
  Non-operating	-40°C to 70°C	-40°C to 70°C
  Relative Humidity	10% to 90%	10% to 90%
  (RH)	non-condensing	non-condensing
  Maximum Wet Bulb	30°C	30°C
  Shock (11 ms)
  Operating	10 G	10 G
  Non-operating	200 G	200 G
  Vibration (0 to peak)
  Operating	2 G	2 G
  Non-operating	10 G	10 G
  Altitude
  Operating	-1,000 to 10,000 feet	-1,000 to 10,000 feet
  Non-operating (maximum)	40,000 feet	40,000 feet
  Physical	Stacked Configuration	15 mm x 51	15 mm x 51
  (HDA & PCB)	mm x 77 mm	mm x 77 mm
  Low Profile Configuration:
  Head Disk	10 mm x 51	12 mm x 51
  Assembly (HDA)	mm x 70 mm	mm x 70 mm
  Electronics Card	7 mm 51 mm	7 mm x 51
  (PCBA)	x 77 mm	mm x 77 mm
  Weight	< 95 grams	< 95 grams

  
  
• [0008]
  The ramp assembly in the Integral Peripheral drives confiscates the outermost diameter of the disk platters. In other designs, the passive latch design allows a magnetic bias that is too strong to permit data recording on the innermost data tracks. These areas are therefore not available for data recording, and severely limit storage capacity.
  
• [0009]
  Further WO-A-91/02 349 discloses a head disk assemby comprising all the features defined in the preamble of claim 1.
  
• [0010]
  It is therefore an object of the present invention to provide a head disk assembly with a single one-and-eight-tenths-inch hard disk platter capable of providing data storage capacity exceeding forty megabytes.
  
• [0011]
  Briefly, an embodiment of the present invention is a head disk assembly (HDA) for magnetically recording data as defined in claim 1.
  
• [0012]
  An advantage of the present invention is that it provides a one-and-eight-tenths-inch hard drive capable of storing in excess of forty megabytes of data.
  
• [0013]
  Another advantage of the present invention is that it provides a low profile drive.
  
• [0014]
  These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment which is illustrated in the various drawing figures.
  • Fig. 1A is a top view of a head disk assembly of the present invention;
  • Fig. 1B is a bottom view of the head disk assembly of Fig. 1A;
  • Fig. 1C is an end view of the head disk assembly of Fig. 1A and shows it mounted to a printed circuit card;
  • Fig. 2 is a top elevation of the head disk assembly of Figs. 1A-1C with the cover removed to show the placement of the internal components;
  • Fig. 3A is a top view of the actuator latch assembly of Fig. 2;
  • Fig. 3B is a side view of the actuator latch assembly of Fig. 3A;
  • Fig. 4A is a top elevation of the head disk assembly of Figs. 1A-1C with the cover, platter, actuator assembly and actuator latch assembly removed to show the placement of the internal components obscured by the platter, actuator assembly and actuator latch assembly in Fig. 2; and
  • Fig. 4B is an end view of the head disk assembly of Fig. 4A.
  
  
• [0015]
  Figs. 1A, 1B and 1C illustrate a head disk assembly (HDA) referred to by the general reference numeral 10 comprising a die-cast aluminum base plate 12, and a die-cast aluminum top cover 14. Top cover 14 includes a breather filter 15 and a recirculating air filter 16. Drive 10 is mounted to a printed circuit card (PCB) 17 and attached with a plurality of fasteners 18 to respective bosses 20 that are integral with the casting of base plate 12. A pancake spindle motor 21 hermetically seals and mounts to base plate 12. The length and width dimensions "L" and "W" of HDA 10 are approximately 70.00 mm long by 50.80 mm wide. Motor 21 may be in the form of the one made for such size disk drive by Nidec Corporation (Japan). A connector 22 connects HDA 10 to external disk controller circuitry (e.g., PCB 17). The height "H" between the bottom of fastener 18 to the top of cover 14 is approximately 12.50 mm: A triangularly shaped desiccant 23 is mounted between base plate 12 and cover 14. A system of recesses are included about the inside of cover 14 to provide the minimum clearances needed for internal components.
  
• [0016]
  Fig. 2 illustrates further components of HDA 10 including a single forty-eight millimeter (48 mm) diameter disk platter 24, an actuator assembly 26, an active latch assembly 28, and a rigid PCB 30. Data recording surfaces on platter 24 are preferably specified to be 1400 Oersteds and is available from Nashua Corporation (Santa Clara, CA), Hitachi Metal Technology (Fremont, CA) and Komag Corporation (Milpitas, CA). A disk clamp 31 holds platter 24 to spindle motor 21. Actuator assembly 26 includes a pair of read/write heads 32 attached to an actuator 33 with a pair of Hutchinson suspensions 34, an actuator coil 36 that works with or against a lower magnetic plate 38, and a ferrous member 40 on a latch arm 41. Heads 32 are preferably model MC-50 as manufactured by Yamaha Corporation (Shizuoka-ken, Japan) or model R-90 as manufactured by Read-Rite Corporation (Milpitas, CA). Plate 38 and ferrous member 40 are made of a material that can be attracted to a magnet, such as iron alloys. Actuator coil 36, lower magnetic plate 38 and an upper magnetic plate (not shown, but parallel to plate 38) form a voice coil motor (VCM) that will move actuator assembly 26 back and forth. Heads 32 are Winchester type heads that load and unload against platter 24 in a parking area inside of any data tracks. The head type is also known in the art as contact start-stop (CSS). A pair of rubber crash stops 42 and 43 limit the rotation of actuator assembly 26. Crash stop 43 is removable such that it can be removed to allow the heads 32 to be unloaded and swung free of platter 24 (which is necessary to remove platter 24 from HDA 10). A first flex circuit 44 (shown on edge in Fig. 2) connects actuator coil 36 to PCB 30. A second flex circuit 45 connects spindle motor 21 (beneath platter 24 in Fig. 2) to PCB 30 (shown more completely in Fig. 4A). A third flex circuit 46 (also shown on edge in Fig. 2) connects a latch actuation coil in latch assembly 28 to PCB 30. Actuator assembly 26 rides on a cartridge ball bearing assembly 47 that is screwed into base plate 12. A plurality of concentric tracks 48 on both surfaces of platter 24 can have data that is read or written by read/write heads 32. In HDA 10 the stroke length is approximately 0.503 inches (12,776 mm). The innermost track 48 is positioned at 0.45 inches (11,43 mm) (radius) and the outermost track is positioned at approximately 0.9 inches (22,86 mm). These positions may be adjusted slightly to suit other constraints. There are sufficient tracks 48 per radial inch, in combination with the number of bits per inch, to yield a capacity at least forty megabytes per platter 24. A more detailed summary of function and performance is presented herein in Table II.
  
• [0017]
  An integrated circuit (IC) 50 includes a preamplifier and is surface mounted to PCB 30. Connector 22 attaches to PCB 30 on the side opposite to the view shown in Fig. 2. Since PCB 30 is rigid, connector 22 is supported and a gasket is fitted around connector 22 to seal it and PCB 30 to base plate 12 to keep out dirt and humidity. Base plate 12 seals along a face 60 to cover 14 with a flat flexible gasket sandwiched between. A lip 62 adjacent to face 60 carries up beyond the gap between base plate 12 and cover 14 and serves to prevent a direct path for radiated electrical interference.
  
• [0018]
  Figs. 3A and 3B illustrate that active latch assembly 28 is comprised of a spring 70, a magnet 72 on an arm 74, a VCM 76, a pair of magnetic plates 78, a pivot shaft 80, a pair of limit arms 82 on lower magnetic plate 78, and a connector 84 at the end of flex circuit 46.
  
• [0019]
  In operation, when spindle motor 21 is shut off, a back electro-motive force (EMF) from motor 21 is used by VCM 36 to rotate actuator assembly 26 in a direction "A" (Fig. 2) and by VCM 76 to rotate latch assembly 28 in a direction "B" (Fig. 3A). Magnet 72 is attracted to ferrous member 40 and keeps arm 74 at the extreme of direction "B", thus locking actuator assembly 26 in a parked position such that heads 32 are inside the innermost of data tracks 48. When starting up from the parked position, a current is sent to VCM 36 which forces actuator assembly 26 in a direction "C" (Fig. 2), separating ferrous member 40 and magnet 72. This allows spring 70 to rotate latch assembly 28 in a direction "D" (Fig. 3A). Therefore ferrous member 40 and magnet 72 separate enough that the magnetic bias between ferrous member 40 and magnet 72 does not interfere with seeks of heads 32 to the innermost of data tracks 48.
  
• [0020]
  Figs. 4A and 4B illustrate HDA 10 without actuator assembly 26, platter 24 and latch assembly 28. The top, spindle side of motor 21 is illustrated. Flex circuit 45 is shown to extend to PCB 30 in the area underneath where platter 24 would otherwise be.

  Formatted Capacity	Per Drive	42.6M bytes
  Per Track	19K bytes
  Functional	Flux Density (FCI)	36K
  Number of Platters	1
  Data Surfaces	2
  Data Tracks per Surface	1,110
  Track Density (TPI)	2,558
  Recording Method	29 zones
  Data Correction	ID Type	CRC
  ID Length	17 bits
  Data Field Type	Reed-Solomon w/CRC
  Method	On-the-Fly and Programmed in Software
  Length (Reed Solomon)	88 bits
  Length (CRC)	16 bits
  Correction Length
  On-the-Fly
  Single Burst	11 bits
  Two Bursts	none
  Software
  Single Burst	31 bits
  Two Bursts	11 bits
  On-the-Fly Detection
  Single Burst	51 bits
  Triple Bursts	11 bits
  On-the-Fly Miscorrection	1 in 10[SUP]20[/SUP] bits
  Performance	Data Rates	12.6M to 24M bits/sec.
  Rotational Speed	5,400 RPM
  Average Seek Time	19 ms
  Track to Track Seek Time	5 ms
  Maximum Seek Time	40 ms
  Buffer Size	32K bytes
  Interleave	1:1
  Interface	ATA/IDE
  Reliability	MTBF
  Recoverable Data	1 in 10[SUP]7[/SUP] (no ECC)
  Error Rate	1 in 10[SUP]9[/SUP] (ECC)
  Non-Recoverable Data	1 in 10[SUP]12[/SUP] (no ECC)
  Error Rate	1 in 10[SUP]13[/SUP] (ECC)
  Non-Recoverable Seek	1 in 10[SUP]6[/SUP]
  Power	Startup	3.5 watts
  Idle	0.88 watts
  Read/Write/Seek	2.1 watts
  Environmental	Temperature
  Operating	5°C to 55°C
  Non-operating	-40°C to 60°C
  Humidity Range
  Operating	8% to 80% non-condensing
  Non-operating	8% to 80% non-condensing
  Maximum Wet Bulb	26°C
  Shock (half sine)	11 ms
  Operating	100 G
  Non-operating	10 G
  Vibration (peak to peak)
  Operating	1 G
  Non-operating	10 G
  Altitude
  Operating	-1000 feet to 10K feet
  Non-operating	-1000 feet to 40K feet
  (maximum)
  Physical	Height	12.7 mm
  Width	50.8 mm
  Length	70.0 mm (HDA)
  Weight	90 grams

  
  
• [0021]
  HDA 10 has the capacity of storing over forty megabytes of data on the two surfaces of platter 24 as a result of writing data over a larger area of platter 24 and at a higher density than that of the prior art. Platter 24 is rotated by motor 21 at 5400 revolutions per minute (RPM). The rotational rate is limited to 5400 by both the increasing power consumed at higher speeds and how fast the integrated electronics can take the data. Present three-channel devices made by National Semiconductor (Santa Clara, CA) are about the fastest available, and faster devices that may be available in the future could allow rates higher than 5400 RPM if the power consumed by spindle motor 21 is not objectionable.
  
• [0022]
  With 36K flux changes per inch (FCI) in data tracks 48, much higher amplitude signals are induced into read/write heads 32 during read operations because the rapid changes in magnetic field will induce higher voltages in the inductors of heads 32. A greater number of tracks per inch (TPI) are possible because the higher read amplitudes permit the magnetic track widths to be narrowed while maintaining acceptable flux change amplitudes. The number of tracks per inch is limited to about 2500 TPI and the number of flux changes per inch is limited to approximately 36,000 by the combination heads and platters that are presently available. No doubt, in time, heads and platters that improve on the preferred ones listed above for heads 32 and platter 24 will become commercially available. Such improvements will increase the storage capacity of HDA 10 substantially above forty megabytes, and are considered to be embraced by the present invention.
  
• [0023]
  Since no part of the outermost diameter of platter 24 is usurped by a head unloading ramp as in the prior art, the outermost areas accommodate additional data tracks 48. The unique configuration of the actuator latch assembly 28 similarly allows the inner most diameter of platter 24 to accommodate additional data tracks 48. A low overhead servo encoding, which is described in detail one of the previously referenced co-pending applications and which are incorporated by reference herein, provides additional increases in the storage capacity of HDA 10. Briefly, the low overhead servo recording technique increases the data storage capacity of each data track 48 by encoding a complete eleven-bit sector address in only one of every seven sectors on a track 48 and an abbreviated four-bit sector address in the other six of the seven sectors. There are typically sixty-four sectors per track 48. The savings in sector overhead is used to add additional data sectors to each data track 48 for more data capacity. The number of bits used for a complete sector address is a function of the number of sectors in a track 48, and the number of bits that can be used in an abbreviation is a function of the ratio of sectors with complete sector addresses to sectors with abbreviated sector addresses. Therefore, variations on the number of bits and the ratios used will no doubt provide the above described benefits of the present invention. For example, track addresses can be similarly abbreviated in a majority of tracks 48.

​

 

[pese]

Hard Disk Crash – What is it?

A hard disk crash, sometimes called hard disk head crash, occurs when the magnetic pickup head meets the platter. Since the platter is spinning at typical speeds of up to 7200 rpm, the head assembly meeting it is the equivalent of a high-speed crash, and the head usually disintegrates. A crash may result in the total destruction of the head or a partial destruction, which is when the drive continues operating, but with reduced reliability.
​

The head normally floats above the platter surface on a cushion of air, and is very delicate. When it touches the surface, the first signs and symptoms may be a sharp high-pitched whistling noise. This noise may gradually turn into a scraping noise.​

When a head crash is imminent or predicted, it is prudent to backup your data straight away whilst the system is online and working. Manuals recommend not switching OFF the computer as the drive may not initialise again.​

Signs and Symptoms of Head Crash

• 
  [*=left]If the drive keeps clicking on power up, then it means that the heads are unable to read the System Area (SA), and therefore unable to initialise. The actuator arm moving between the inner and outer tracks trying to read the SA causes the clicking sound.
  [*=left]If it keeps parking, then it means that the drive components have failed and the system parks the heads as a safety measure.
  [*=left]If you have lost your iTunes music, or Microsoft Office, or QuickBooks, or everything, then a crash may have corrupted the file system. Data recovery software may be able to recover some of the data.
  [*=left]A crashed head that is partially working may return corrupted data producing blue screens and data dumps. The error codes normally point to corrupted data.
  [*=left]If the head quality test returns poor figures, then that is also a good indicator of a head crash.

Causes of Crash

​

• 
  [*=left]For Laptops and mobile devices, impact whilst powered is usually the cause of the drive crash. I have come across MacBook Pro, iMac, PS3, and Xbox 360 damaged by children dropping them.
  [*=left]For old servers, the motor bearings gradually wear out reducing the gap between the head and the platter. You could arrive to work in the morning and hear a whistling noise, which is a very good indicator.
  [*=left]Virus attack is also a very common reason for a drive to keep crashing. Viruses designed to cause damage may crash the drive.

Data Recovery Software

A totally destroyed head requires replacement and data recovery software tools will not work for a drive with an inoperable head, because the drive may not initialise or read anything. If all you are hearing is a clicking sound then it means that the drive is not initialising and recovery software will not help​

If the crash only partially damaged the heads, then there is a chance that recovery software may be able to read some of the data.​

How to Fix

Unfortunately, replacing the head is something that only the factory can carry out and some professional data recovery services.​

They typically replace the head assembly from an identical drive, and laboratory grade dust free environments are required to carry out such work.​

Head Replacement

On a multi-platter drive, the heads are neatly stacked together as shown above. Professionals sometimes call this a “head-stack​