Archive for the ‘Hard disk Data Recovery’ Category
Friday, November 20th, 2009
1, the system does not recognize the hard disk
Can not start from the hard disk from the A disk can not boot into the C drive, use the CMOS the automatic monitoring function can not be found in the presence of the hard disk. Most of these failures appear in the connecting cable or IDE port on the mouth, the hard disk itself is very small failure rate and can be re-plug hard drive cable or a change of IDE port and cable to replace the test, can quickly find fault lies. If the new hard drive connected to the non-recognition, there is a common reason for this is the main hard disk from the line, if the hard disk drive connected to the IDE’s main location, then the hard drive-based disk-to jump, jumper error generally can not be detected the hard disk.
2, CMOS failure caused by
CMOS direct impact on the correctness of the normal use of the hard disk, here mainly refers to the type in which the hard disk. Fortunately, the machines now support the “IDE auto detect” feature that can automatically detect the hard disk type. When you connect a new hard drive or replace a new hard disk by this function must be re-set type. Of course, some types of motherboards can automatically identify the type of hard drives. When the hard disk type error, and sometimes simply can not start the system, and sometimes be able to start, but it will read and write error occurred. Such as CMOS, the type of hard drive is less than the actual hard disk capacity, then the hard drive behind the sector will not be able to read and write, if it is multi-regional state of the individual partitions will be lost. There is also a major cause of the malfunction, since the current logical arguments support the type of IDE hard disk can be used Normal, LBA, Large and so on. If the normal mode, installed the data, but in the CMOS, replaced by other models, the hard disk read and write errors occur failure, because of its physical geological mapping has changed, and will not be able to read the original location of the correct hard drive .
3, the master boot program is causing the boot failure
Hard disk master boot sector is one of the most sensitive parts, one of the primary boot program is a part of it, this section is primarily used to detect the hard disk partition program correctness, and to determine active partition, is responsible for guiding the right to transferred to the active partition to DOS or other operating systems. This section will be unable to process damaged boot from the hard drive, but after the soft areas or light areas on the hard drive can read and write. Ways to fix this fault is more simple, the use of high version of the DOS-fdisk the most convenient, as with parameters / mbr run-time will have a direct replacement (rewritable) hard disk master boot program. In fact the hard disk master boot sector is the establishment of this program, fdisk. exe into a complete hard disk that contains the master boot program. While the DOS version of the constantly updated, but the hard disk master boot process has not changed from DOS 3. x to the present winDOS 95 of the DOS, so long as to find a DOS boot disk to start the system and run this program can be repaired. In addition, other tools, like kv300 also have this feature.
4, partition table boot boot failure error
The hard disk partition table errors are serious errors, different errors might lead to different types of losses. If there is no active partition flag, then the computer does not start. However, the soft areas or light areas on the hard disk after boot the system read and write, through fdisk to reset the active partition to be repaired. If it is a partition type of error could result in the loss of a partition. The fourth partition table for the partition type byte value, the normal bootable DOS partition larger than 32mb the basic value of 06, while the extended DOS partition value is 05. If the basic DOS partition type to 05 can not start the system, and can not read and write data on them. If DOS does not recognize 06 types of change, such as efh, the DOS Partition that change is not a DOS partition, of course, can not read and write. Many people take advantage of this type of value is to achieve a single partition encryption technology to restore the original values of the right type can make the partition back to normal. The partition table there are other data are used to record the start or termination of the address of partition. These data will result in damage to the partition of the confusion or loss of, generally can not be manually restored, the only way is to backup the data to re-write the partition table back, or from other conditions the same type and the same hard disk partition to obtain data on the partition table, otherwise will result in permanent loss of other data. In the master boot sector to do so, nu can use tools such as software, the operation is very convenient and can be directly on the hard disk master boot sector to read and write or edit. Of course, debug can be used to operate, but the operation cumbersome and has certain risks.
5, area of effective symbol errors caused by hard disk failure
In the hard disk master boot sector there are still an important part, that is its last two bytes: 55aah, this word for the sector and effective logo. When from the hard disk, floppy disk or optical zone starts, will detect these two bytes, if there think there is a hard disk exists, otherwise it would not recognize the hard disk. This flag will be transferred from the hard disk boot rom basic or tip into the floppy disk. Can not boot from a floppy disk into the hard disk. Here can be used for the entire hard drive encryption technology. Debug methods can be used to resume processing. In addition, DOS boot sector is still such a flag is present, when the DOS boot sector not leading marks, the system starts will appear as: “missing operating system”. Of its repair methods available to the primary boot sector repair methods, but addresses a different, more convenient way is to use the following DOS system, a common repair method.
6, DOS boot boot failures caused by
DOS boot system is mainly from the DOS boot sector and the DOS system files. System files include iosys, msdos.sys, command.com, which is a DOS shell command.com file, can be used to replace other similar documents, but the default state is essential DOS boot files. DOS in Windows 95 systems carry, msdos.sys is a text file, is to start windows to document. But only when you can not boot DOS file. But the DOS boot error, it can boot from a floppy disk or CD-ROM, then use the sys c: transmission system failures can be repaired, including the boot sector and system files can be automatically repaired to normal.
7, FAT table to read and write failures caused by
fat table records the hard disk data storage addresses, each file has a set of connection to specify its stored fat chain cluster address. fat content of the document the table means that the loss of damage. Fortunately, the DOS system itself offers two fat tables, if the current use of the fat table is damaged, can be used to cover the second repair. However, due to different specifications of the disk of its fat table length and the second fat tables do not have fixed addresses, so the repair must be correct to find its correct position, by a number of tools, such as nu and others who have such a repair function, use was also very convenient. Debug can also be used to achieve this operation, that is using its m command of the second fat at the table can be moved to the first table. If the second fat table also damaged, you can not put the hard disk back to its original state, but the file data is still stored in the hard disk data area, can use the command chkdsk or scandisk to repair and eventually get *. chk files, this is the loss of fat chain sector data. If it is a text file can be extracted from the full document can be merged, if it is a binary data file, it is difficult to restore a complete file.
8, table of contents to guide the damage caused failure
Table of Contents record the name of the file on your hard disk and other data, the most important one is the starting cluster number of the document, the directory table because there is no automatic backup feature, so if the directory is damaged a large number of documents will be lost. Of a method also used to reduce the loss of the above method of chkdsk or scandisk programs from the hard drive search out the chk files, table of contents damaged by the cluster number is the first loss, in the case of fat for the damage formed chk files are generally more complete file data, each one chk file that is a complete document, its original name changed to restore most of the documents.
9, accidentally deleted partition data recovery
When using fdisk to delete the hard disk partition, the superficial is the hard drive data has completely disappeared, without formatting the hard disk will be displayed when entering an invalid drive. If you know fdisk works, you know, fdisk the hard drive just to rewrite the master boot sector (sector 0 face 0 1) in content. Specifically, that is to remove the hard disk partition table information, while the hard disk of any partition of data are not changed, can be modeled the above-mentioned repair partition table wrong approach, that is to find ways to restore the partition table data can be restored the original sub – area that is data, but only limited to the addition or re-partition after the partition. If you already have on the partition formatted with the format, after an earlier recovery partition, in accordance with the following methods of data recovery partition.
10, mistakenly formatted hard disk data recovery
In the DOS version of the high state, the formatting operation format in the default state, have been established for recovery formatted disk information, is actually the disk DOS boot sector, fat partition table and copy all the contents of the table of contents to the last few sectors of the disk (because the latter sector is rarely used), while the contents of the data area has not changed. This by running the “unformat c:” you can restore the original file allocation table and the table of contents, thus completing the hard drive information recovery. Another DOS also provides a miror disk command is used to record the current information for the formatted or deleted after the resumption of the use of this method is also more effective
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Friday, November 20th, 2009
Like all hard disks, Western Digital hard drive will fail in a variety of ways. Documented below are symptoms we have found specific to Western Digital hard disk drives:
Electronic: An electronic fault may develop on the controller board – this is often caused by the spindle motor. The failure will often involve multiple components. With failures of this type the drive will appear dead and not be recognised by the BIOS. We have produced an example PDF document that further details an example electronic failure on Western Digital hard disk drives
Firmware: This is the microcode that makes the drive function correctly. Sometimes it is prone to corruption which makes the drive (and data on it) inaccessible. Drives with firmware corruption will often have some of the following symptoms:
o be recognised incorrectly in the BIOS, the computer will then often hang
o be recognised as 0 bytes in size
o not be recognised at all in the BIOS
o run slowly make a regular ticking noise at start up
Western Digital external Hard Drive are available for different desktops and portable devices. These drive come shipped with SATA, SCSI and IDE interfaces. Different hard drive families are MOMMOTH, SABRE, HAWK, SCORPIO and BUCCANEER. At times, you observe that the system that is installed with a Western Digital external hard drive fails to detect it.
BIOS no longer recognizes it, you come across failure error messages, you observe typical scratching and grinding noises from drive or the drive appears to be completely dead. In such situations, it is required that you immediately replace the drive as it might be physically damaged and consult Western Digital Hard drive data Recovery technicians to extract lost data manually.
For example, when you try to start the laptop installed with a Western Digital drive, you might fail to do so with the following error:
“WDC ROM MODEL–< drive family name >”
Here, ‘ drive family name’ denotes the name of Western Digital hard drive family.
Cause
Such errors are the general indicative of physical hard drive failure. You receive this error in BIOS screen that is generated by PCB controller board when it cannot detect the it healthy. Few possible causes for such behavior are:
1.Hard drive ROM is corrupted
2.Corruption of one or more firmware modules
3.One of more read/write heads are faulty
Solution
You need to follow these steps in order to recover from the failure:
1.Power down the system as soon as possible
2.Detach the drive from the system
3.Install a new drive
4.Pack the failed drive in anti-static and anti-shock material and send it to a reliable company providing Data Recovery Services
A Hard Drive data Recovery company aim at repairing and recovering all possible data from a physically crashed drive. Using proprietary tools and advanced recovery techniques, these companies are competent to recover from hard drive failure in all cases. The general methods used are examining the failed drive in Clean Rooms, determining the odds of recovery and nature of problem, repairing or replacing damaged internals and so forth.
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Tuesday, November 10th, 2009
The basic physical construction of a hard disk drive consists of spinning disks with heads that move over the disks and store data in tracks and sectors. The heads read and write data in concentric rings called tracks. These tracks are divided into segments called sectors, which normally store 512 bytes each.
The tracks and sectors on a disk.
Hard disk drives usually have multiple disks, called platters, that are stacked on top of each other and spin in unison, each with two sides on which the drive stores data. Most drives have one, two, or three platters, resulting in two, four, or six sides. The identically aligned tracks on each side of every platter together make up a cylinder. A hard disk drive normally has one head per platter side, with all the heads mounted on a common carrier device or rack. The heads move radially across the disk in unison; they cannot move independently because they are mounted on the same carrier or rack, called an actuator.
Hard disk cylinders.
Originally, most hard disks spun at 3,600rpmapproximately 10 times faster than a floppy disk drive. For many years, 3,600rpm was pretty much a constant among hard drives. Now, however, most drives spin even faster. Although speeds can vary, modern drives normally spin the platters at either 4,200, 5,400, 7,200, 10,000, or 15,000rpm. Most standard-issue drives found in portable systems spin at the slower 4,200 or 5,400rpm speeds, with a few high performance models now available that spin at 7,200rpm. The 10,000 or 15,000rpm drives are normally found only in very high performance desktop-based workstations or servers, where their higher prices, heat generation, and noise can be more easily dealt with. High rotational speeds combined with a fast head-positioning mechanism and more sectors per track are what make one hard disk overall faster than another.
The heads in most hard disk drives do not (and should not!) touch the platters during normal operation. However, on most drives, the heads do rest on the platters when the drive is powered off. In most drives, when the drive is powered off, the heads move to the innermost cylinder, where they land on the platter surface. This is referred to as contact start stop (CSS) design. When the drive is powered on, the heads slide on the platter surface as they spin up, until a very thin cushion of air builds up between the heads and platter surface, which causes the heads to lift off and remain suspended a short distance above or below the platter. If the air cushion is disturbed by a particle of dust or a shock, the head can come into contact with the platter while it is spinning at full speed. When contact with the spinning platters is forceful enough to do damage, the event is called a head crash. The result of a head crash can be anything from a few lost bytes of data to a completely ruined drive. Most drives have special lubricants on the platters and hardened surfaces that can withstand the daily “takeoffs” and “landings” as well as more severe abuse.
Some newer drives do not use CSS design and instead use a load/unload mechanism, which does not allow the heads to contact the platters, even when the drive is powered off. First used in the 2.5-inch form factor notearticle or laptop drives, where resistance to mechanical shock is more important, load/unload mechanisms use a ramp positioned just off the outer part of the platter surface. When the drive is powered off or in a power-saving mode, the heads ride up on the ramp. When powered on, the platters are allowed to come up to full speed before the heads are released down the ramp, allowing the airflow (air bearing) to prevent any head/platter contact.
Because the platter assemblies are sealed and nonremovable, the track densities on the disk can be very high. Hard disks today have up to 96,000 or more tracks per inch (tpi) recorded on the media (for example, Hitachi Travelstar 80GN). Head disk assemblies (HDAs), which contain the platters, are assembled and sealed in clean rooms under absolutely sanitary conditions. Because few companies repair HDAs, repair or replacement of the parts inside a sealed HDA can be expensive. Every hard disk ever made eventually fails. The only questions are when the failure will occur and whether your data is backed up.
Tracks and Sectors
A track is a single ring of data on one side of a disk. A disk track is too large to manage data effectively as a single storage unit. Many disk tracks can store 100,000 or more bytes of data, which would be very inefficient for storing small files. For that reason, tracks are divided into several numbered divisions known as sectors. These sectors represent arc-shaped pieces of the track.
Various types of disk drives split their disk tracks into different numbers of sectors, depending on the density of the tracks. For example, floppy disk formats use 836 sectors per track, although hard disks usually store data at a higher density and today can have 900 or more sectors per track physically. The sectors created by the standard formatting procedure have a capacity of 512 bytes, which has been one constant throughout the history of the PC. In order to be compatible with most older BIOS and drivers, drives will usually perform an internal translation so that they pretend to have 63 sectors per track when addressed in CHS (cylinder, head, sector) mode.
The sectors on a track are numbered starting with 1, unlike the heads or cylinders that are numbered starting with 0. For example, a 1.44MB floppy disk contains 80 cylinders, numbered 079, and two heads, numbered 0 and 1, whereas each track on each cylinder has 18 sectors numbered 118.
When a disk is formatted, the formatting program creates ID areas before and after each sector’s data that the disk controller uses for sector numbering and for identifying the start and end of each sector. These areas precede and follow each sector’s data area and consume some of the disk’s total storage capacity. This accounts for the difference between a disk’s unformatted and formatted capacities. Note that most modern hard disks are sold preformatted and advertise only the formatted capacity. The unformatted capacity is usually not mentioned anymore. Another interesting development is that many new drives use what is called No-ID sector formatting, which means that the sectors are recorded without ID marks before and after each sector. This means that more of the disk can be used for actual data.
Each sector on a disk normally has a prefix portion, or header, that identifies the start of the sector and contains the sector number, as well as a suffix portion, or trailer, that contains a checksum (which helps ensure the integrity of the data contents). Many newer drives omit this header and have what is called a No-ID recording, allowing more space for actual data. With a No-ID recording, the start and end of each sector are located via predetermined clock timing.
Each sector contains 512 bytes of data. The low-level formatting process normally fills the data bytes with some specific value, such as F6h (hex) or some other repeating test pattern used by the drive manufacturer. Some patterns are more difficult for the electronics on the drive to encode/decode, so these patterns normally are used when the manufacturer is testing the drive during initial formatting. A special test pattern might cause errors to surface that a normal data pattern would not show. This way, the manufacturer can more accurately identify marginal sectors during testing.
The sector headers and trailers are independent of the operating system, the file system, and the files stored on the drive. In addition to the headers and trailers, gaps exist within the sectors, between the sectors on each track, and also between tracks, but none of these gaps contain usable data space. The gaps are created during the low-level format process when the recording is turned off momentarily. They serve the same function as having gaps of silence between the songs recorded on a cassette tape. The prefix, suffix, and gaps account for the lost space between the unformatted capacity of a disk and the formatted capacity. For example, a 2MB (unformatted) floppy has a formatted capacity of 1.44MB, and an older 20GB unformatted capacity hard disk (for instance, a Quantum Fireball LCT20) has a capacity of only 18.3GB when it is formatted. Because the ATA and SCSI hard disks you purchase today are low-level formatted at the factory, the manufacturers now advertise only the formatted capacity. Even so, nearly all drives use some reserved space for managing the data that will be stored on the drive.
Tags: Hard disk Data Recovery
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Tuesday, November 10th, 2009
Currently, 3.5-inch drives are the most popular for desktop whereas the 2.5-inch and smaller drives are popular in laptops and other portable devices. Parallel ATA 3.5-inch drives are quickly being phased out to be replaced by Serial ATA drives, which are now the most commonplace drive interface in new desktop systems, while note articles are just beginning to transition towards 2.5-inch drives featuring the Serial ATA interface. Part of the reason most laptop systems continue to support Parallel ATA is that until recently the motherboard chipsets only supported Parallel ATA natively, and adding an extra chip for SATA support was cost, space, and power prohibitive. Not to mention that there were originally no SATA 2.5-inch drives on the market as well. But that is changing. The 900 series chipsets from Intel found in newer systems include native SATA support, and SATA 2.5-inch drives are now available as well.
5.25-Inch Drive
Shugart Associates first introduced the 5.25-inch form factor along with the first 5.25-inch floppy drive back in 1976. The story goes that Founder Al Shugart then left that company and founded Seagate Technologies, which introduced the first 5.25-inch (Model ST-506, 5MB capacity) hard disk in 1980, predating the IBM PC. IBM later used the Seagate ST-412 (10MB) drive in some of its PC-XT models, which were among the very first PCs to be sold with hard disks built in. The physical format of the 5.25-inch hard disk back then was the same as the 5.25-inch full-height floppy drive, so both would fit the same size bay in a chassis. For example, the original IBM PC and XT models had two 5.25-inch full-height bays that could accept these drives. The first portable systems (such as the original Compaq Portable) used these drives as well. Later, the 5.25-inch form factor was reduced in height by one-half when the appropriately named 5.25-inch half-height floppy drives and hard disks were introduced. This allowed two drives to fit in a bay originally designed for one. The 5.25-inch half-height form factor is still used as the form factor for modern desktop CD-ROM and DVD drives, and is the standard form factor for the larger drive bays in all modern desktop PC chassis. Early portable PCs (such as the IBM Portable PC) used this form factor as well.
3.5-Inch Drive
Sony introduced the first 3.5-inch floppy drive in 1981, which used a smaller width and depth but the same height as the half-height 5.25-inch form factor. These were called 3.5-inch half-height drives, even though there was no such thing as a “full-height” 3.5-inch drive. Rodime followed with the first 3.5-inch half-height hard disk in 1983. Later 3.5-inch floppy and hard disks would be reduced in height to only 1 inch, which was just under one-third of the original 5.25-inch full-height form factor (these were sometimes called 1/3-height drives). Today, the 1-inch-high version has become the modern industry standard 3.5-inch form factor.
2.5-Inch Drive
PrairieTek introduced the 2.5-inch form factor in 1988, which proved to be ideal for laptop computers. As laptop sales grew, so did sales of the 2.5-inch drives. Although PrairieTek was the first with that form factor, other drive manufacturers quickly capitalized on the market by also introducing 2.5-inch drives. Finally, in 1994 Conner Peripherals Inc. paid $18 million for PrairieTek’s 2.5-inch disk drive technology, and PrairieTek went out of business. Since the 2.5-inch drives first appeared, virtually all laptop systems used them. Although 2.5-inch drives can also be used in desktop systems, the 3.5-inch drive continues to dominate the desktop market due to greater capacity and speed along with lower cost.
The 2.5-inch drives have been manufactured in various thicknesses (or heights), and many laptop systems are restricted as to how thick a drive they will support. Here are the common thicknesses that have been available:
- 8.5mm
- 9.5mm
- 12.5mm
- 12.7mm
- 17.0mm
- 19.0mm
By far the popular sizes are 9.5mm and 12.5mm, which are the sizes used by most laptop. Currently, most drive manufacturers are concentrating on the 9.5mm form factor. A thinner drive can almost always be installed in place of a thicker one; however, most systems will not have the room to accept a thicker drive than they were originally designed to use.
1.8-Inch Drive
The 1.8-inch drive was first introduced by Integral Peripherals in 1991 and has had problems gaining acceptance in the marketplace ever since. This size was initially created because it fit perfectly in the PC Card (PCMCIA) form factor, making it ideal as add-on removable storage for laptop systems. Unfortunately, the 1.8-inch drive market has been slow to take shape, and in 1998 an investment group called Mobile Storage bought Integral Peripherals 1.8-inch drive technology for $5.5 million, and Integral Peripherals went out of business. Several other companies have introduced 1.8-inch drives over the years, most notably HP, Calluna, Toshiba, and Hitachi. Of those, only Toshiba and Hitachi continue to manufacture drives in that format. HP exited the disk drive market completely in 1996, and Calluna finally ceased operation in 2001. Toshiba introduced its 1.8-inch drives (available in the physical format of a Type II PC-Card) in 2000, and Hitachi entered the 1.8-inch drive market in 2003. The 1.8-inch drives are available in capacities of up to 60GB or more, and depending on the model can be used anywhere a standard PC Card can be plugged in.
1-Inch Drives
During 1998, IBM introduced a 1-inch drive called the MicroDrive, incorporating a single platter about the size of a quarter! Current versions of the MicroDrive can store up to 4GB or more. These drives are in the physical and electrical format of a Type II Compact Flash (CF) card, which means they can be used in almost any device that takes CF cards, including digital cameras, Personal Digital Assistants (PDAs), MP3 players, and anywhere else Compact Flash memory cards can be used. IBM’s disk drive division was sold to Hitachi in 2003 and combined with Hitachi’s storage technology business as Hitachi Global Storage Technologies.
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Tuesday, November 10th, 2009
In 1957, Cyril Northcote Parkinson published his famous compilation of essays titled Parkinson’s Law, which starts off with the statement, “Work expands so as to fill the time available for its completion.” A corollary of Parkinson’s most famous “law” can be applied to hard disks: Data expands so as to fill the space available for its storage. This, of course, means that no matter how big a drive you get, you will find a way to fill it. I have lived by that dictum since purchasing my first hard disk drive over 20 years ago.
Although I am well aware of the exponential growth of everything associated with computers, I am still amazed at how large and fast modern drives have become. The first hard disk I purchased in 1983 was a 10MB (that’s 10 megabytes, not gigabytes). The Miniscribe model 2012 was a 5.25-inch (platter) drive that was about 8″x5.75″x3.25″ (203mmx146mmx83mm) in overall size and weighed 5.5 lb. (2.5kg). That’s heavier than some of today’s laptop computers! By comparison, one of the biggest drives available to date, the 500GB Hitachi 7K500 SATA drive uses smaller 3.5-inch platters, is about 5.75″x4″x1″ (146mmx102mmx25mm) in overall size, weighs only 1.54 lb. (0.70kg), and stores a whopping 500GB, which is 50,000 times more storage in a package that is about one-sixth the size and one-fourth the weight of my old Miniscribe. By another comparison, a 160GB 2.5-inch Seagate Momentus 5400.3 160 drive uses even smaller 2.5-inch platters, is about 3.94″x2.76″x0.37″ (100mmx70mmx9.5mm) in overall size, weighs only 0.22 lb. (99g), and stores 160GB, which is 16,000 times more storage in a package that is about 37 times smaller and 1/25th the weight of my first drive.
Obviously the large storage capacities found on modern drives are useless unless you can also transfer the data to and from the disk quickly. The hard disk as found in the original IBM XT in 1983 had a constant data transfer rate from the media of about 100KBps. Today, most commonly used drives feature the Serial Ata interface offering variable media data transfer rates of up to 66MBps (average rates are lower, up to about 50MBps). Much like the increase in drive capacity the speed of the interface has also come a long way since the MFM and RLL interfaces that were commonplace in the ’80s. As always, the interfaces are much faster than the actual drives. The Parallel ATA, Serial ATA, and SCSI interfaces are commonplace nowadays offer data transfer rates of up to 133MBps for Parallel ATA, 150 and 300MBps for Serial ATA and 320MBps bandwidth for Ultra-320 SCSI. All of these interfaces are much faster than the drives they support, meaning that the true transfer rate you will see is almost entirely limited by the drive and not the interface you choose. The modern interfaces have bandwidth to spare for future developments and advances in hard disk technology.
In summary, it is clear that these are pretty large steps in just over 20 years time!
To give you an idea of how far hard disks have come in the past 20 years, I’ve outlined some of the more profound changes in hard disk storage:
- Maximum storage capacities have increased from the 5MB and 10MB 5.25-inch full-height drives available in 1982 to 500GB in 2005 for 3.5-inch half-height drives (Hitachi 7K500, 500GB SATA), 160GB for notearticle system with 2.5-inch drives (Seagate Momentus 5400.3 160), and 60GB for 1.8-inch drives (Toshiba MK-6006GAH, 60GB). Hard disks smaller than 40GB are rare in desktop or even laptop systems.
- Data-transfer rates to and from the media (sustained transfer rates) have increased from about 100KBps for the original IBM XT in 1983 to an average of 50MBps for some of the fastest drives today (Western Digital Raptor WD74GD) or more than 80MBps for the fastest SCSI drive (Seagate Cheetah 15K.4).
- Average seek times (how long it takes to move the heads to a particular cylinder) have decreased from more than 85ms (milliseconds) for the 10MB drives used by IBM in the 1983 vintage PC-XT to 3.3ms for some of the fastest drives today (Seagate Cheetah 15K.4).
- In 1982 and 1983, a 10MB drive and controller cost more than $2,000 ($200 per megabyte), which would be more than double that in today’s dollars. Today, the cost of desktop hard disks (with integrated controllers) has dropped to 0.05 cent per megabyte or less, or about 100GB for $50. Laptop drives have fallen to 0.1 cents per megabyte or less, or about 100GB for $100!
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