Label Mib
Hard Disk Drive
History
Main article: History of hard disks
HDDs (introduced in 1956 as data storage for an IBM accounting computer) were originally developed for use with general purpose computers. During the year 1990, the need for large-scale, reliable storage, independent of a particular device, led to the introduction of embedded systems such as RAID, Network Attached Storage (NAS) systems and storage area network (SAN) systems that effectively and reliable access to large amounts of data. In the 21st century, HDD usage extended to consumer applications such as camcorders, mobile phones (eg Nokia N91), digital audio players, digital video players, digital video recorders, personal digital assistants and video game consoles.
Technology
Schematic representation of a hard disk
HDDs record data by magnetizing ferromagnetic material oriented to represent either a 0 or a 1 binary digit. They read the data back by detecting the magnetization of the material. A typical HDD design consists of a pivot holder of one or more flat circular disks called platters, the data are recorded. The discs are made of a non-magnetic material, usually aluminum or glass, and are coated with a thin layer of magnetic material, typically 1020 Nm in thickness for reference, can standard copy will be between 0.07 millimeter (70,000 nm) and 0.18 millimeters (180,000 nm) thick. with an outer carbon layer for protection. Older disks used iron (III) oxide as the magnetic material, but current disks use a cobalt alloy. [Quote necessary]
A view of the magnetic surface in action. This If the binary data encoded using frequency modulation.
The disks are spun at very high speeds. Information is written to a dish as it runs past devices called read / write heads that are very active (tens of nanometers in new stations) close over the magnetic surface. The read and write is used to detect and immediately change the magnetization of the material below. There is one head for each magnetic platter surface on the axle, mounted on a common arm. An actuator arm (or access arm) moves the heads on an arc (roughly radially) on the platters as they spin, allowing each head to access almost the entire surface of the disk if it is running. The arm is moved using a voice coil actuator or in some older models, a stepper motor.
The magnetic surface of each platter is conceptually divided in many small sub-micrometer-sized magnetic regions, each used for a binary unit of information to encode. Initially, the regions were oriented horizontally, but beginning about 2005, the orientation was changed to perpendicular. Due to the polycrystalline nature of the magnetic material each of these magnetic regions is composed from a few hundred magnetic grains. Beads are typically 10 nm in size, each forming a single magnetic domain. Each magnetic region total represents a magnetic dipole, which a highly localized magnetic field nearby. A write head magnetizes a region by generating a strong local magnetic field. Early HDDs used an electromagnet both for the region and magnetize the magnetic field, then read using electromagnetic induction. Later versions of inductive heads included metal in Gap (MIG) heads and thin film heads. As data density increased, the heads using magnetoresistance (MR) operation, the electrical resistance of the head adapted to the strength of the magnetism of the plateau. Later development made use of spintronics, in these heads, the magnetic resistance effect head technology was much larger than previous types, and was renamed "giant" magnetoresistance (GMR). In the minds of today, the read and write elements are separate, but in the immediate vicinity, on the body of an actuator arm. The read element is typically magneto-resistive while the write element is typically thin-film inductive.
HD heads are kept in contact with the platter surface air very close to the disk, the air moving, or close to, the platter speed. [Citation needed] The recording and playback head are mounted on a block called a slider, and the surface near the plateau has been formed to keep it barely in contact. It is a kind of air is supplied.
In modern drives, the small size of the magnetic regions creates the danger that their magnetic state would be lost due to thermal effects. Counteract this, the platters lined with two parallel magnetic layers, separated by a 3-atom thick layer of non-magnetic element ruthenium, and the two layers are magnetized in opposite directions, thus reinforce each other. Another technology used to overcome thermal effects to a greater recording densities perpendicular recording, the first delivery in 2005, starting in 2007 the technology was used in many HDDs.
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The grain boundaries appear to be very important in HDD design. The grains are very small and close together, so the coupling between neighboring grains is very strong. When a grain is magnetized, neighboring grains tend to be adjusted parallel to it or demagnetized. Then both the stability of the data and signal to noise ratio will be sabotaged. A clear boundary may weaken the link between the grains and then increase the signal to noise ratio. In longitudinal recording, the single-domain grains uniaxial anisotropy with easy axes in the film plane. The result of this arrangement is that in addition to magnets repel each other. Therefore, the magnetostatic energy is so large that it is difficult to increase areal density. Perpendicular recording media, on the other hand, the easy axis of the grains oriented perpendicular to the disk plane. Adjacent magnets attract each other and magnetostatic energy are much lower. Yes, much higher areal density can be achieved in perpendicular recording. Another unique feature in perpendicular recording is a soft magnetic layer included in the recording disk. This layer is used to conduct writing magnetic flux, so that writing is more efficient. This will be discussed in writing. Therefore a higher anisotropy medium of film, such as L10-FePt and rare-earth magnets are used.
Error Handling
Modern disks also make extensive use of error correcting codes (ECC) especially Reedolomon error correction. These techniques to store extra bits for each block of data that are determined by mathematical formulas. The extra bits can be found many errors. Although this extra bit space on the hard disk, they have a higher recording densities should be applied, resulting in far greater storage capacity for user data. In 2009, The latest drives are low-density parity-check codes (LDPC), Reed-Solomon crowd. LDPC codes performance near the Shannon limit and therefore provide the highest storage density available.
Typical hard drives attempt to "reassign" the data in a physical sector which is a poor physical reserve sectoropefully while the number of errors that bad sector is still small enough that the ECC can completely recover the data without loss. The SMART system counts the total number of errors in the entire hard disk defined by ECC, and the total number remapping, in an attempt to predict the hard drive.
See also: FileSystem
Architecture
A hard disk with the platters and the motor hub removed when the copper coils around a stator in the middle of the spindle motor. The orange stripe along the side of the arm is a thin printed-circuit cable. The pivot bearing in the center.
A typical hard disk has two electric motors, one for a spin the disks and the position of the read / write head assembly. The drive motor has an external rotor to the platters, the stator windings are fixed instead. The actuator has a read-write head under the tip of the very end (near center), a thin printed-circuit cable connects the read-write head at the hub of the drive. A flexible, somewhat 'u' shape, ribbon cable, seen edge-on below and on the left side of the actuator arm in the first image and more clearly in the second, the connection of the head to the controller board on the other side.
The main arm is very light but rigid; in modern drives, acceleration at the head reaches 550 Gs.
Open hard drive with top magnet removed, showing heads of copper coil actuator (upper right).
The silver structure on the left corner of the first image is the cover of the permanent magnet and moving coil motor that swings the heads to the desired position (it has been demonstrated removed in the second figure). The record supports a thin neodymium-iron-boron (NIB) high-flux magnets. Beneath this plate is the moving coil, often called the voice coil to analogy of the coil in the speakers, attached to the actuator hub, and below that is half NIB magnet mounted on the base of the engine (some stations are only a magnet).
The voice coil itself is shaped rather like an arrowhead, and made of double coated coppmagnet [clarification] thread. The inner layer is insulation, and outer is thermoplastic, which bonds the coil together after being wound on a form, making it self-supporting. The parts of the coil along the two sides of the arrowhead (Die point to the actuator bearing center) interaction with the magnetic field, the development of a tangential force that rotates the actuator. Flow radially outward along one side of the arrowhead, radially inwards and the other produces the tangential force. (See # magnetic field force on a charged particle.) When the magnetic field were uniform, each side would generate opposing forces would cancel each other. Therefore the surface of the magnet is half N pole, half S pole, the radial dividing line in the middle, allowing the two sides of The coil can be seen opposing magnetic fields produce forces and to add instead of cancel. Currents along the top and bottom of the coil to produce radial forces which do not rotate the head.
Capacity and access speed
PC hard drive capacity (in GB) over time. The vertical axis is logarithmic, so the fit line corresponds to exponential growth.
Using rigid disks and sealing the unit allows much tighter tolerances than in a floppy drive. Consequently, hard disks to store much more data than floppy disk drives and can access and pass them faster.
As of April 2009 [update], the highest capacity consumer HDDs are 2 TB.
A typical "desktop HDD" can store between 120 GB and 2 TB, although rarely exceeds 500 GB of data (based on U.S. market data), runs from 5400 to 15,000 rpm and have a media transfer rate of 0.5 Gbit / s or higher. (1 GB = 109 bytes, 1 Gbit / s = 109 bit / s)
The fastest transparent plug HDDs run at 10,000 or 15,000 rpm, and can achieve sequential media transfer speeds above 1.6 Gbit / s. and a sustained transfer rate up to 1 Gbit / s. Drives spin at 10,000 or 15,000 rpm use smaller plates to reduce more power (as they have less air resistance) and thus generally have a lower capacity than the highest capacity desktop drives.
"Mobile Hard Drives", ie, laptop hard drives, which are physically smaller than their desktop counterparts and business, tend to slow and to have a lower capacity. A typical mobile hard drive spins at 4200rpm or, 5400rpm or 7200rpm, 5400rpm with the most prominent. 7200rpm drives are more expensive and lower capacity, while 4200rpm models usually have a very high storage capacities. Because physically smaller dish (s), mobile HDDs generally have lower capacity than their larger desktop counterparts.
The exponential increase in disk space and data access at speeds of HDDs have enabled the the commercial viability of consumer products that need large storage capacity, such as digital video recorders and digital audio players needed. In addition, the availability of large amounts of cheap storage made viable a variety of web-based services with extraordinary capacity requirements, such as free-of-charge web search, web archiving and sharing videos (Google, Internet Archive, YouTube, etc.).
The most important way to decrease access time for the speed increase, so the rotational delay, while the main way to increase throughput and storage density is increasing. Based on historical trends, analysts predict a further growth in the HDD bit density (and therefore the capacity) of approximately 40% per year. Access times are not kept up with throughput increases, which themselves have not kept pace with the growth of storage capacity.
The expected output of all HDD Random IOPS can be calculated by the sum of 1000 msec average seek time and average rotational latency.
The first 3.5 HDD marketed as able to store 1 TB was the Hitachi Deskstar 7K1000. It contains five platters at approximately 200 GB each, 1 GB (935.5 GB) of usable space, depending on the difference between the capacity in decimal units (1 TB = 1012 bytes) and binary units (1 TiB = 1024 GB = 240 bytes). Hitachi has now joined by Samsung (Samsung SpinPoint F1, which has 3 334 GB platters), Seagate and Western Digital in the 1 TB drive market.
In September 2009, Showa Denko announced improvements in capacity platters they produce for HDD makers. A single 2.5 "platter is capable to 334 GB of data into value, and the preliminary results for 3.5" indicate a 750 GB per platter capacity.
Form Factor
Width
Largest Capacity
Platters (Max)
5.25 FH
146 mm
47 GB (1998)
14
5.25 HH
146 mm
19.3 GB (1998)
4
3.5 SATA
102 mm
2 TB (2009)
5
3.5 PATA
102 mm
750 GB (2006)
?
2.5 SATA
69.9 mm
1 TB (2009)
3
2.5 PATA
69.9 mm
320 GB (2009)
?
1.8 SATA
54 mm
320 GB (2009)
3
1.8 PATA / LIF
54 mm
240 GB (2008)
2
1.3
43 mm
40 GB (2007)
1
1 (CFII / ZIF / IDE Flex)
42 mm
20 GB (2006)
1
0.85
24 mm
8 GB (2004)
1
Capacitance measurements
A disassembled and labeled 1997 hard drive. All major components are placed on a mirror, which the new symmetrical reflections.
Raw unformatted capacity of a hard drive is usually quoted with SI prefixes (metric system prefixes), increasing by powers of 1000, today it usually means gigabytes (GB) and terabytes (TB). This is common for data speeds and memory sizes not inherently produced in the power of two sizes, like RAM and flash memory. Hard drives, however, have no inherent capacity binary format as determined by the number of heads, tracks and sectors.
This can lead to some confusion, because some operating systems, the report of the formatted capacity of a hard drive using binary prefixed units that increase the powers of 1024.
A one terabyte (1 TB) hard disk drive would be expected to be around 1 trillion bytes (1,000,000,000,000) or 1000 UK to hold, and indeed most 1 TB hard drives will contain something more than this number. However, some operating system utilities would be just about 931 GB or 953 674 MB, whereas the correct units would be 931 GB or 953,674 MB. (The actual number for a formatted capacity will be slightly smaller still, depending on the file system). Below the appropriate ways of reporting a terabyte.
SI prefixes (HDD)
equivalent
Binary prefixes (OS)
equivalent
1 TB (terabytes)
1 * 10 004 B
0.9095 TiB (Tebibytes)
0.9095 * 10 244 B
1000 GB (gigabytes)
1000 * 10 003 B
931.3 GiB (Gibibytes)
931.3 B * 10243
1,000,000 megabytes (MB)
1000000 * 10002 B
953,674.3 MiB (Mebibytes)
953,674.3 * 10,242 B
1000000000 KB (kilobytes)
1000000000 * 1000 B
976,562,500 KB (Kibibytes)
B 976 562 500 * 1024
1,000,000,000,000 B (bytes)
–
1,000,000,000,000 B (bytes)
–
Microsoft Windows reports disk capacity both in one figure to 12 or more digits and prefix in binary units to three significant figures.
The capacity of a hard disk calculated by multiplying the number of cylinders by the number of heads by the number of sectors by the number of bytes / sector (usually 512). Drives with the ATA interface and a capacity of eight gigabytes or more behave as if they were structured into 16383 cylinders, 16 heads and 63 sectors for compatibility with older operating systems. Unlike the year 1980, cylinder, head, sector (C / H / S) has reported to the CPU by a modern ATA drive is no longer the actual physical parameters since the reported numbers are constrained by historic operating system interfaces and with zone bit recording the actual number of sectors varies by zone. Disks with SCSI interface address each sector with a unique whole number, the operating system remains ignorant of their head or cylinder count.
The old C / H / S scheme has been replaced by logical block addressing. In some cases, to try the C / H / S scheme "force-fit" with large capacity disks, the number of heads given as 64, although no modern drive has anywhere near 32 platters.
Formatted disk overhead
For a formatted disk, the operating system's file internal use is another, though small, why a computer hard drive or other storage device capacity can be as different as the theoretical capacity to show. This would include storage, as examples, a file allocation table (FAT) or inodes, and other operating system data structures. This file is usually less than 1% overhead on disks larger than 100 MB. RAID disks, data integrity and fault-tolerance requirements also reduce the actual capacity. Thus, a RAID1 disk about half the total capacity due to data mirroring. Voor RAID5 drives with x-stations you would lose 1 / x from your space to parity. RAID drives are several disks that are displayed on a ride to the user, but provides fault-tolerance.
A general rule of thumb of the manufacturer's hard drive capacity to quickly convert standard Microsoft Windows formatted capacity is 0.93 * capacity hard disk manufacturer for less than a terabyte HDD and 0.91 * capacity of the hard disk of the HDD manufacturer's equal to or greater than 1 terabyte.
Form Factors
5 Full-height 110 MB HDD,
2 (8.5 mm) 6495 MB HDD
US / UK pennies for comparison.
Six hard drives with 8, 5.25, 3.5, 2.5, 1.8, and 1 disks, partially disassembled to show platters and read-write heads, with a ruler with inches.
Before the era of PCs and small computers, hard drives were of widely differing sizes, typically in freestanding cabinets the size of washing machines (eg December RP06 Disk Drive) or designed so that the dimensions placement on a 19 "rack (eg Diablo Model 31).
With increasing sales of small computers with built-in floppy disk drives (FDDs), hard drives that would fit the FDD fasteners desirable, and this led to the evolution of the market to stations with certain form factors, primarily derived from the sizes of 8 " 5.25 "and 3.5" floppy disk drives. Sizes smaller than 3.5 "have emerged as popular in the market and / or by various private sector organizations.
8 inches: 9.5 in 4624 in 14.25 in (241.3 mm 117.5 mm 362 mm)
In 1979, Shugart Associates' SA1000 was the first form factor compatible HDD, same dimensions and a compatible interface for the FDD 8.
5.25 inches: 5.75 to 1.63 in 8 in (146.1 mm 41.4 mm 203 mm)
This smaller form factor, first used in an HDD by Seagate in 1980, the same size as full height 5-inch diameter FDD, which is 3.25 inches high. This is twice as high as "half height" commonly used Today, that is, 1.63 in (41.4 mm). Most desktop models of drives for optical 120 mm disks (DVD, CD) use half the height dimension 5, but fell out the fashion for HDDs. The Quantum Bigfoot HDD was the last to use it in the late 1990s, with ow-profile (25 mm) and ltra-low-profile (20 mm) high versions.
3.5 inch: 4 in 1 in 5.75 inches (101.6 mm 25.4 mm 146 mm) = 376.77344 cm
This smaller form factor, first used in an HDD by Rodime in 1984, was same size as the "half height" 3 FDD, ie, 1.63 inches high. Today has been largely replaced by 1-inch high-profile limline or ow versions of this form factor used by most desktop HDD.
2.5 inch: 2.75 to 0.3740.59 in 3945 in (69.85 mm 715 mm 100 mm) = 48.895104.775 cm3
These smaller form factor was introduced in 1988 by PrairieTek, there is no corresponding FDD. It is widely used today for hard drives in mobile devices (laptops, music players, etc.) as of 2008 replacing 3.5 inch enterprise-class drives. It is also used in the Xbox 360 and Playstation 3 video game consoles. Today, the dominant height of this form factor is 9.5 mm for laptop drives, but high-capacity drives (750 GB and 1 TB) have a height of 12.5 mm. Enterprise-class drives a height of 15 mm. Seagate has a thin 7mm drive aimed at entry-level high-end laptops and netbooks in December 2009.
1.8 inch 54 mm 8 mm 71 mm = 30.672 cm
This form factor, originally introduced by Integral Peripherals in 1993, has become the ATA-7 LIF with dimensions as indicated. It is increasingly used in digital audio players and subnotebooks. An original variant exists 25-GB hard drives that fit directly into a PC card slot. This became popular for use in iPods and other HDD based MP3 players.
1 inch: 42.8 mm 5 mm 36.4 mm
This form factor was introduced in 1999 as IBM's Microdrive to fit in a CF Type II slot. Samsung calls the same form factor "1.3 inch" drive in its product literature.
0.85 inch: 24 mm 5 mm 32 mm
Toshiba announced this form factor in January 2004 for use in mobile phones and similar applications, including SD / MMC card slot compatible HDDs optimized for video storage on 4G handsets. Toshiba currently sells a 4 GB (MK4001MTD) and 8 GB (MK8003MTD) version and the Guinness World Record for the smallest hard drive.
3.5 "and 2.5" hard drives that currently dominate the market.
By 2009 all manufacturers had ceased to develop new products for the 1.3-inch, 1-inch and 0.85-inch form factors due to falling prices of flash memory.
The inch-based nickname All these factors are usually not indicate any actual product dimension (which are in millimeters more recent form factors), but only about a size indicate relative to disk diameters, in the interest of historical continuity.
Other Features
Transfer speed
As of 2008 a typical 7200rpm desktop hard drive has sustained a "disk-to-buffer data transfer rate of about 70 megabytes per second. This rate depends on the track located, so will most of the data on the outer tracks (where more data sectors) and lower towards the inner tracks (where there is less data sectors), and is generally slightly higher for 10,000 rpm drives. A current standard scale used for the buffer-to-computer "interface is 3.0 Gbit / s SATA, which is about 300 megabytes can / S from the buffer to send to the computer, and is still comfortably ahead of the current disk-to-buffer transfer rates. Transfer rate (read / write) can be measured by writing a large file to disk using special tools file generator, back to reading the file. Transmission rate can be affected by the file system fragmentation and the layout of the files.
Seek Time
Seek time currently ranges from just under 2 ms for high-end server drives, to with 15 ms for miniature drives, with the most common desktop type typically being around 9 ms. [Citation needed] There is not a significant improvement in this rate for several years. Some early PC drives used a stepper motor to the heads, and consequently had access times slower than 80,120 ms, but this was soon improved by voice coil type of operation in late 1980, making access time to about 20 ms.
Power Consumption
Power consumption has become increasingly important, not only in mobile devices such as laptops, but also in server and desktop markets. Increasing data center machine density has led to problems delivering sufficient power to devices (especially for spin up) and reducing the waste heat subsequently produced, as well as environmental and electrical cost concerns (see green computing). Similar problems exist for large companies with thousands of desktop PCs. Smaller form factor drives often use less power than larger drives. An interesting development in this field for controlling the speed, so head comes to their destination just in time to read the sector, rather than arriving as quickly as possible and then having to wait for the sector to come around (ie rotational delay). Many of the hard drive companies are now producing green Drives that much less power and cooling needs. Many of these slower spin Green Drive ' (<5400 RPM compared to 7200 RPM, 10,000 RPM and 15,000 RPM) and less waste heat.
In the Server and Workstation systems where there may be multiple hard drives, There are several ways to check if the hard drives spin up (highest power).
On SCSI drives, the SCSI controller directly control spin up and spin down the disks.
On Parallel ATA (aka PATA) and SATA hard drives, which support Power-up in the standby or PUI. The hard disk will not run until the controller or system BIOS gives a specific command to do so. This reduces power consumption or the power.
Newer SATA hard drives, there Staggered spin-up function. The hard disk will not run until the SATA PHY is ready (communication with the host controller starts). [Citation needed]
To further control or reduce power consumption and consumption, the hard disk can be spun into its energy consumption.
Audible noise
Measured in decibels, audible noise is important for certain applications such as PVRs, digital audio recording and quiet computers. Low noise disks typically use fluid bearings, slower rotational speeds (typically 5400 rpm) and speed to search under load (AAM) to reduce audible clicks and crunching sounds. Drives in smaller form factors (eg 2.5 inch) are often quieter than larger disks.
Shock
Shock resistance is especially important for mobile devices. Some laptops now active hard disk protection that parks the disk heads if the machine is put down, hopefully before impact, to supply every chance to survive in such a case. Maximum shock tolerance to date is 350 Gs of operating 1000 GS and non-operational.
Access and interfaces
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Hard disks are accessed over one of a number of bus types, including parallel ATA (P-ATA, also called IDE or EIDE), Serial ATA (SATA), SCSI, Serial Attached SCSI (SAS) and Fibre Channel. Bridge circuit is sometimes used to hard drives Connecting buses that they can not communicate with natively, such as IEEE 1394, USB and SCSI.
For the ST-506 interface, the system encrypts data written to the disc surface was also important. The first ST-506 disks used Modified Frequency Modulation (MFM) encoding, and transferred data at a rate of 5 megabits per second. Later controllers with 2.7 RLL (Or just "RLL") encoding causes 50% more data appear under the heads compared with a rotation of an MFM drive, increasing data storage and data transfer by 50% to 7.5 megabits per seconds.
Many ST-506 interface drives were only specified by the manufacturer to run on the 1/3th lower MFM data transfer rate compared with RLL, while others drive models (usually more expensive versions of the same drive) were specified to run at the higher RLL data transfer rate. In some cases, a station had sufficient margin around the MFM specified model to run with the denser / faster RLL data transfer rate (not recommended nor guaranteed by manufacturers). Also, each RLL-certified disk rotates every MFM controller, but with 1 / 3 less data capacity and as much as 1/3rd less data transfer rate compared to its specifications RLL.
Enhanced Small Disk Interface (ESDI) also supported multiple data rates (2.7 RLL ESDI drives always, but at 10, 15 or 20 megabits per second), but this was usually onderhandeld automatically by the disk and the controller, most of the time, but 15 or 20 megabit ESDI drives were not backward compatible (ie a 15 or 20 megabit drive would not run on a 10 megabit controller). ESDI drives typically also had jumpers to the number of sectors per track and move (in some cases) sector size.
Modern hard drives a consistent interface for the rest of the computer, any data encoding scheme is used internally. Typically a DSP in the electronics inside the hard drive takes the raw analog voltages from the read head and uses PRML and Reedolomon error correction decoding of the sector boundaries and sector data, which sends data from the default interface. That DSP also watches the error rate detected by error detection and correction, and performs bad sector remapping, data collection for Self-Monitoring, Analysis, and Reporting Technology, and other internal functions.
SCSI was originally Only an alert frequency of 5 MHz for a maximum data rate of 5 megabytes per second over 8 parallel conductors, but later this was increased dramatically. The SCSI bus speed did not affect the internal hard drive speeds due to buffering between the SCSI bus and drive the internal data bus, but much of the first drives were very small buffers, and had to be formatted to a different interleave (just like ST-506 disks) when used on slow computers, such as early Commodore Amiga, IBM PC compatibles and Apple Macintosh.
ATA drives are usually no problems with interleave or data rate, due to their controller design, but many early models were incompatible with each other and have not put two devices running on the same physical cable in a master / slave setup. This was largely remedied by the mid-1990s, when ATA specification standardized was and the details began to be cleared, but still causes problems occasionally (especially with CD-ROM and DVD-ROM discs, and mixing of Ultra DMA and non-UDMA devices).
Serial ATA does away with master / slave setups entirely, placing each disk on its own channel (with its own set of I / O ports) instead.
FireWire / IEEE 1394 and USB (1.0/2.0) HDDs are external units generally ATA or SCSI disks with ports on the back allowing very simple and effective expansion and mobility. Most FireWire / IEEE 1394 models are able to daisy-chain to continue adding peripherals without requiring additional ports on the computer itself. USB is a network of point-point and is not allow for looping. USB hubs are used to increase the number of available ports and are used for devices that do not need to load, since the current supplied by hubs is usually less than what is available through the built-in USB ports.
Disk interface families used in personal computers
Notable families of disk interfaces include:
Historical bit serial interfaces connecting a hard disk drive (HDD) to a hard disk controller (HDC) with two cables, one for control and a data. (Each station also has an extra cable for power, usually directly on the food). The HDC important functions, such as serial / parallel conversion, separation data, and track format, and update to the disk (after formatting) in order to ensure reliability. Each control cable, two or more disks, while a special (and smaller) data cable serves each station.
ST506 uses MFM (Modified Frequency Modulation) for data encryption method.
ST412 is available In MFM or RLL (Run Length Limited) variants encode.
Enhanced Small Disk Interface (ESDI) was an interface developed by Maxtor to allow faster communication between the processor the disk than MFM and RLL or possible.
Modern bit serial interfaces to connect a hard drive interface to a host bus adapter (today typically integrated in the "south bridge") with a data / control cable. (As above historical bit serial interfaces, each station has an additional power, usually directly to the diet.)
Fibre Channel (FC) is a successor to parallel SCSI interface on enterprise market. It is a serial protocol. In disk drives usually Fibre Channel arbitrated loop (FC-AL) connection topology is used. FC has much broader use than just hard disk interfaces, and it is the cornerstone of storage area networks (SAN). Recently other protocols for this field, like iSCSI and ATA over Ethernet are so well developed. Confusingly, drives usually use copper twisted-pair cables for Fibre Channel, not fiberglass. The latter are traditionally reserved for larger devices such as servers or disk array controllers.
Serial ATA (SATA). The SATA data cable has a few dates for differential transferring data to the device, and a differential pair for receiving the unit, just like EIA-422. This requires that data be transmitted serially. Similar differential signaling is used in RS485, LocalTalk, USB, Firewire and SCSI differential.
Serial Attached SCSI (SAS). The SAS is a new generation serial communication protocol for devices designed for a much higher speed data transfers and is compatible with SATA. SAS uses a mechanically identical data and power connector to standard 3.5 "HDDs SATA1/SATA2, and many server-based SAS RAID controllers are also capable of dealing with SATA hard drives. SAS uses serial communication instead of the parallel method found in traditional SCSI devices but still uses SCSI commands.
Become a serial interface to connect a hard disk to a host bus adapter (today typically integrated into the "south bridge") with a cable for combined data / control. (As with all bits serial interfaces above, each station has an additional power, usually directly to the diet.) The earliest versions of these interfaces typically had an 8-bit parallel data to / from the station, but 16-bit versions were much more common, and there are 32 bit versions. Modern versions have serial data transfer. The word nature of data transfer makes the design of a host bus adapter significantly simpler than that of the precursor HDD controller.
Integrated Drive Electronics (IDE), later renamed to ATA, with the alias P-ATA (Parallel ATA) retroactively added after introduction of the new variant Serial ATA. The original name reflected the innovative integration HDD controller with HDD itself, which was not found in earlier disks. Moving the HDD controller from the interface card to the drive helped to standardize interfaces, and the cost and reduce complexity. The 40 pin IDE / ATA connection transfers 16 bits of data at a time on the cable. The data cable was originally 40 conductor, but later a requirements for higher speed data transfer to and from the hard drive has led to an "ultra DMA" mode, known as UDMA. Gradually faster versions of this standard ultimately added the requirement for a variant of the same 80 conductor cable, where half of the conductors provides a grounding necessary for enhanced high-speed signal quality by reducing of crosstalk. The interface for 80 conductor has only 39 pins, the missing pin as a key to prevent incorrect insertion of the connector to an incompatible socket, a common cause of disk and controller damage.
EIDE had an unofficial update (by Western Digital) to the original IDE standard, with the main improvement is the use of direct memory access (DMA) to transfer data between the disk and the computer to transfer without the intervention of the CPU, an improvement later adopted by the official ATA standards. By directly transferring data between memory and disk, DMA eliminates the need for the CPU to copy byte by byte, so that the process of other tasks while the data transfer.
Small Computer System Interface (SCSI), originally named SASI for Shugart Associates System Interface, was an early competitor van ESDI. SCSI disks were standard on servers, workstations, Commodore Amiga and Apple Macintosh computers through the mid-'90s, by which time most models had changed to IDE (and later, SATA) family disks. Only in 2005 did the capacity of SCSI disks fall behind IDE disk technology, but the highest performance disks are still available in SCSI and Fibre Channel only. The length limitations of the data cable allows for external SCSI devices. Originally SCSI data cables used single ended (common mode), data transmission, but server class SCSI differential transmission can be either Low Voltage Differential (LVD) or high voltage differential (HVD). ("Low" and "High" voltage for differential SCSI over SCSI standards and will not meet the meaning of low voltage and high voltage as used in general electrical engineering contexts, as applicable, such as the statutory electrical codes, both LVD and HVD use low voltage signals (3.3 V and 5 V, respectively) in general terms.)
Acronym or abbreviation
Sense
Description
SASI
Shugart Associates System Interface
Historical predecessor of SCSI.
SCSI
Small Computer System Interface
Bus oriented that handles concurrent operations.
SAS
Serial Attached SCSI
Improving SCSI, uses serial communication instead of parallel.
ST-506
Seagate Technology
Historical Seagate interface.
ST-412
Seagate Technology
Historical Seagate interface (minor improvement over ST-506).
ESDI
Enhanced Small Disk Interface
Historical; ST-412/506 backward compatible, but faster and more integrated.
ATA
Advanced Technology Attachment
Successor ST-412/506/ESDI by integrating the disk controller is completely on your device. Incapable of concurrent operations.
SATA
Serial ATA
Modification of ATA, uses serial communication instead of parallel.
Integrity
An IBM HDD head resting on a disk platter. Since the drive not in use, the head is simply pressed against the disk by the suspension.
Close-up of a hard disk head resting on a disk platter. A reflection of the head and suspension is visible on the mirror-like disk.
Because of the very narrow space between the head and disk surface, any contamination of the read-write heads or platters can lead to a head crash a failure of the disk where the head scrapes on the platter surface, often grinding away the thin magnetic film and causing data loss. Head crashes can be caused by electronic failure, a sudden power failure, shock, abrasion, corrosion, or poorly manufactured platters and heads.
spindle The HDD's system is based on air pressure inside the enclosure to support the heads at their proper flying height while the disk rotates. Hard drives require a specific range of the air pressure to function properly. The connection to the external environment and pressure is via a small hole in the enclosure (about 0.5 mm in diameter), usually with a filter the inside (the breather filter). If the pressure is too low, there is not enough lift for the flying head, so the head too close to the disc, and there is a risk of head crashes and data loss. Specially manufactured sealed and pressurized disks are needed for reliable operation at high altitudes, above about 3,000 meters (10,000 feet). Modern drives are: temperature sensors and adjust their operation to the operational environment. Vent holes can be seen on all disks, they usually have a sticker next to them, warn the user to cover the holes. The air in the operating drive is constantly changing also being swept in motion by friction with the spinning platters. This air passes through an internal recirculation (or "recirc") filter to remove residual contaminants in the manufacture, particles or chemicals that somehow may have entered the housing, and any particles or outgassing generated internally in normal operation. Very high humidity for extended periods can corrode the cups and saucers.
For giant magnetic resistance head technology (GMR) heads in particular, a minor head crash from contamination (not the magnetic surface of the disc removed) still results the head temporarily overheating, due to friction with the disk surface, and the data unreadable for a short period until the head temperature stabilizes (so called "Thermal sharpness", a problem that can partly be addressed by proper electronic filtering of the read signal).
Control of moving arm
The hard disk drive electronics of the movement of the actuator and the rotation of the disk, and perform reads and writes at the request of the disk controller. Feedback from the drive electronics is achieved by means of specific segments of the disc devoted to feedback servo. These are totally concentric circles (in the case of special servo technology) or segments interspersed with real data (in the case of embedded servo technology). The servo feedback optimizes the signal to noise ratio of the GMR sensor by adjusting the voice coil the operated arm. The spinning of the disk also uses a servo motor. Modern disk firmware is capable of reading plans and writes efficiently on the platter surfaces and remapping sectors of the media who have failed.
Landing zones and load / unload technology
A read / write head of a circa-1998 Fujitsu 3.5 "hard drive. The area shown is about 2.0 mm x 3.0mm.
Microphotograph of an older generation hard disk head and slider (1990). The size of the front (which is the trailing face "of the slider) is about 0.3 mm, 1.0 mm. It is the location of the actual 'head' (magnetic sensors). The non-visible bottom of the slider is approximately 1.0 mm 1.25 mm (so-called "nano" size) and faces the platter. It contains the lithographically micro-machined air bearing surface (ABS) with which the slider to flying in a very controlled manner. A functional part of the head is round, orange structure visible in the middle – the lithographically defined copper coil of the write transducer. Also note the electric connections by wires connected to gold pads.
Modern hard drives to prevent outages and other disruptions from the landing of their heads in the data area by parking the heads, or in a landing zone or unloading (ie, loading / unloading) heads. Some early PC HDDs not automatically park the heads and they would land on data. In some other early units, the user manually park the heads by running a program to park the HDD heads.
A landing zone is an area of the platter usually near its inner diameter (ID), where no data is stored. This area is called the Contact Start / Stop (CSS) zone. Drives are designed so that both a spring or, more recently, rotational inertia in the platters is used to park the heads in case of unexpected power outages. In this case, the spindle motor temporarily acts as a generator to power the actuator.
The spring tension of the head mounting constantly pushes the heads towards the plateau. While the disk rotates, the heads are supported by an air bearing and experience no physical contact or wear. CSS floats in the sliders of head sensors (often just called heads) are designed for a number of landings and takeoffs from the media surface to survive, but wear and tear on these microscopic components eventually takes its toll. Most manufacturers design the sliders to survive 50,000 contact cycles before the chance of damage on startup rises above 50%. However, the decay rate is not linear: if a disk is younger and less start-stop cycles, but a better chance of surviving the next startup than an older, higher-mileage drive (as the head literally drags along the disk surface until the air bearing is established). For example, the Seagate Barracuda 7200.10 series of desktop hard disks rated to 50,000 start-stop cycles, in other words, no errors attributed to the main plate interface were seen before at least 50,000 start-stop cycles during testing.
Around 1995 IBM pioneered a technology where a landing zone the disc is made by a precision laser process (Laser Zone Texture = LZT) producing an array of smooth nanometer-scale "bumps" in a landing zone, thus vastly improving stiction and wear performance. This technology is still largely in use today (2008), predominantly in desktop and enterprise (3.5 inch) discs. In general CSS technology can be prone to increased stiction (the tendency for the heads to stick to the platter surface), for example due to increased humidity. Excessive stiction could cause physical damage to the platter and slider or spindle motor.
Load / unload technology relies on the heads are lifted off the platters into a safe location, and thus the risks of wear and stiction whole. The first HDD RAMAC and most early disk drives used complex mechanisms for loading and unloading of the heads. Modern hard drives using loading platform, first introduced by Memorex in 1967, loading / unloading on plastic "ramps" near the outer disk edge.
All HDDs today still use one of these two technologies mentioned above. Each has a list of advantages and disadvantages in terms of loss of storage on disk, the relative difficulty of mechanical tolerance control, non-operational shock resistance, the cost of implementation, etc.
Addressing shock resistance, IBM is also a technology for their ThinkPad line of laptop computers called the Active Protection System. When a sudden, sharp movement is detected by the built-in accelerometer in the Thinkpad, internal hard disk heads automatically unload themselves to reducing risk of any loss of data or scratch defects. Apple later used this technology in their PowerBook, iBook, MacBook and MacBook Pro series, known as the Sudden Motion Sensor. Sony, HP their HP 3D Drive Guard and Toshiba have released similar technology in their notebook computers.
This accelerometer-based shock sensor is also used for building low-cost earthquake sensor networks.
Disk failures and their metrics
Wikibooks has a book on the subject of
Minimizing hard disk failure and data loss
Most major hard disk and motherboard manufacturers now support SMART (Self-Monitoring, Analysis, and Reporting Technology), which measures characteristics such as drive temperature, spin-up time, the data error rates, etc. Some of the trends and sudden changes in these parameters thought to be associated with an increased risk of drive failure and data loss.
However, not all failures are predictable. Normal use eventually can lead to a breakdown in the inherently fragile device, making it essential for the user to periodically back up the data on another storage device. Doing so will result in the loss of data. Although it is sometimes possible to recover lost information, it is normally a very costly procedure, and it is not possible to guarantee success. A 2007 study published by Google suggested little correlation between tariffs and non-high temperature or activity, but the correlation between manufacturer / model and failure was relatively strong. Statistics in this case is very kept secret by most entities. Google does not know the manufacturer names along with their respective failure rates, although since they were found to Hitachi Deskstar drives used in some of their servers. While several SMART parameters have an impact on the probability of failure, a Much of failed drives do not produce predictive SMART parameters. SMART parameters alone are not useful for predicting individual drive failures.
A much common misconception is that a hard drive cooler will last longer than a warmer disk. The Google study seems to imply the opposite "lower temperatures are associated with higher failure rates. "Hard drives with SMART-reported average temperatures below 27 C (80.6 F) had higher default rates than hard drives with the highest reported average temperature of 50 C (122 F), not at least twice as high as the optimal SMART-reported temperature of 36 C (96.8 F) to 47 C (116.6 F).
SCSI, SAS and FC drives are typically more expensive and are traditionally used in servers and disk arrays, while low-cost ATA and SATA drives evolved in the home computer market and were seen as less reliable. This distinction is becoming blurred.
The mean time between failure (MTBF) of SATA drives is usually about 600,000 hours (some drives, Western Digital Raptor as were 1.2 million hours MTBF) measured, while SCSI drives are suitable for top of 1.5 million hours. [Citation needed] However, independent research indicates that MTBF is not a reliable estimate of the life of one's drive. MTBF is conducted in the laboratory environments in test chambers and is an important measure to improve the quality a hard drive to fix it before in high volume production. Once the drive product is in production, more valid metric is annualized failure rate (AFR). [Citation needed] AFR The percentage of real-world drive failures after shipping.
SAS drives are similar to SCSI drives, with a high MTBF and high reliability. [Citation needed]
Enterprise SATA drives are designed and manufactured for enterprise markets, unlike standard SATA drives have reliability comparable to other enterprise class drives.
Typically enterprise drives (all companies drives, including SCSI, SAS, enterprise SATA and FC) experience between 0.70% -0.78% annual failure rates for the total disks installed. [Citation needed]
Ultimately, all mechanical hard drives fail. And with the strategy to reduce the loss of data redundancy is to have in one form or another, such as RAID and backup. RAID should never be used as a backup such as RAID controllers also break, allowing the disks inaccessible. After a backup strategy, such daily differential and weekly full backups, the only sure way to prevent data loss.
Manufacturers
Western Digital 250 GB 3.5-inch SATA HDD. This particular model is equipped with both SATA and Molex power inputs.
Seagate hard drives are manufactured in a factory in Wuxi, China
See also List from on-defunct hard disk manufacturers
The technological resources and know-how required for modern drive development and production mean that as of 2010, almost all Hard drives in the world are produced by only five big companies: Seagate, Western Digital, Hitachi, Samsung and Toshiba.
Dozens of former HDD manufacturers have gone from the company, merger, or closed HDD divisions; as capacities and demand for products increased, profits became hard to find, and the market underwent a significant consolidation in the late 1980 and late 1990. The first prominent victim of the company in the PC era was Computer Memories Inc., or CMI, after an incident with faulty 20 MB AT disks In 1985, CMI's reputation never recovered, and they leave the HDD business in 1987. Another interesting fact was Miniscribe, which went bankrupt in 1990 after it was found to be guilty had made in the accounting fraud and inflated sales figures for several years. Many other smaller companies (such Kalok, Micro Science, Lapin, Areal, Priam and PrairieTek) also not survive the shakeout, and disappeared in 1993, Micropolis was able to stop until 1997, and JTS, a relative latecomer to the scene, lasted only a few years and disappeared In 1999, after attempting to manufacture HDDs in India. Their claim to fame is creating a new 3 form factor drive for use in laptops. Quantum and Integral also invested 3 in the form factor, but ultimately not support this form factor when not to strike. Rodime was also a major manufacturer in the year 1980, but stopped making disks In the early 1990 amidst the shakeout and now concentrates on technology licensing, they keep a number of patents related to 3.5-inch form factor HDDs.
The following is the genealogy of the current HDD Businesses
1967: Hitachi, the HDD business.
1967: Toshiba, the HDD business.
1979: Seagate Technology was founded by a group of ex-ex-IBM and Memorex people.
1988: Western Digital (WDC), then a famous designer, the HDD controller over the Tandon Corporation by disk manufacturing division.
1989: Seagate Technology, Control Data's HDD business purchases.
1990: Maxtor Miniscribe purchase of a bankruptcy, so the core of its low-end HDDs.
1994: Quantum Storage Division DEC's purchases, making it a high-end disk range to go with the more consumer-oriented ProDrive range.
1996: Seagate takes Conner Peripherals in a merger.
2000: Maxtor acquired Quantum HDD business, Quantum continues in the tape business.
2003: Hitachi acquires majority of IBM's disk drive division, which was renamed Hitachi Global Storage Technologies (HGST).
2006: Seagate acquires Maxtor.
2009: Toshiba Fujitsu HDD division takes
Sales
In the year 2007 516.2 million hard drives were sold.
See also
Automatic Acoustic Management
Binary prefixes (KiB, MiB, GIB, etc.)
Click of death
Data Disposal
Disc Format
Station Assignment
du (disk usage unix program)
External hard drives
File System
HDD Recorder
History of the hard drives
Hybrid drive
IBM 305 RAMAC
kilobyte, megabyte, gigabyte definition
Multimedia
Solid-state Drive
Spintronics
Write precompensation
References
^ This is the original date of filing of the application which resulted to U.S. Patent 3,503,060, generally accepted as the final drive patent, see Kean, David W., "IBM San Jose, fourth century of innovation, 1977.
^ Other terms used to describe hard disk drives, disk file, DASD (Direct Access Storage Device), fixed disk, CKD disk and Winchester Disk Drive (after the IBM 3340).
^ Webopedia.com
^ Techtarget.com
^ How hard disks work, howstuffworks.com
^ In the year 1990 there was a partial return to use of removable hard drives, such as the Iomega Jaz and REV drives and disks and SyJet and SyQuest Sparq drives and disks, and the Castlewood Orb drive and disk, among other models, but from 2009 these are mostly defunct.
^ IBM.com IBM 350 disk storage unit
^ "Thickness of a piece of paper", HyperTextbook.com
^ "IBM OEM MR Head | Technology | The era of giant magnetic resistance head technology headlines. Hitachigst.com. 27/08/2001. http://www.hitachigst.com/hdd/technolo/gmr/gmr.htm. Retrieved 3/13/2009.
^ Brian Hayes, Terabyte Territory, American Scientist, Vol 90 No 3 (May-June 2002) p. 212
^ "Press Releases December 14, 2004. Toshiba. http://www.toshiba.co.jp/about/press/2004_12/pr1401.htm. 03/13/2009 fetched.
^ "Seagate Momentus 2" HDDs per webpage in January 2008 ". Seagate.com. 10/24/2008. Http: / / www.seagate.com/www/en-us/products/laptops/momentus/. 13/03/2009 fetched.
^ "Seagate Baracuda 3" HDDs Web by January 2008. Seagate.com. Http: / / www.seagate.com/www/en-us/products/desktops/barracuda_hard_drives/. 03/13/2009 fetched.
^ "Western Digital Scorpio 2 "and 3 Green Power" HDD's quarterly conference, July 2007. Wdc.com. Http://www.wdc.com/en/company/investor/q108remarks.asp. 03/13/2009 retrieved.
^ Storage Review – Error Correcting Code
^ Hitachi – "read Channel Iterative Detection Technology in Hard Disk Drives
^ Murph, Darren (2009-01-26). "2TB Western Digital Caviar Green HDD for sale in Australia." Engadget.com. http://www.engadget.com/2009/01/26/western-digitals-2tb-caviar-green-hdd-on-sale-in-australia. 03/13/2009 fetched.
^ PC Magazine comparison of 136 desktops shows 60 in this series HDD capacity with 50 large and 26 smaller capacities), PCMag.com
^ ab Seagate Cheetah 15K.5
^ Walter, Chip (July 25, 2005). "Kryder's Law". Scientific American (Verlagsgruppe Georg von Holtzbrinck GmbH). http://www.sciam.com/article.cfm?articleID=000B0C22-0805-12D8-BDFD83414B7F0000&ref=sciam&chanID=sa006. 10/29/2006 fetched.
^ "Outlines the future Seagate Storage:: Articles:: www.hardwarezone.com. www.hardwarezone.com
^ "Hitachi 7K1000 Terabyte hard drive ". Tomshardware.com. Http://www.tomshardware.com/2007/04/17/hitachi_7k1000_terabyte_hard_drive/. 03/13/2009 fetched.
^ "Seagate Samsung 1 TB Desktop Hard Drives Ship Home ". Dailytech.com. Http://www.dailytech.com/Article.aspx?newsid=7740. 03/13/2009 fetched.
^ "WD Caviar GP: The "Green" 1 TB drive. Tomshardware.com. http://www.tomshardware.com/2007/10/11/wd_caviar_gp/. 13/03/2009 fetched.
^ "SDK Start Shipments of 2.5-inch 334 GB HD Media. Http://www.sdk.co.jp/aa/english/news/2009/aanw_09_1152.html. 15/09/2009 fetched.
^ Seagate Elite 47, shipped 12/97 per 1998 Disk / Trend Report – Rigid Disk Drives
^ Quantum Bigfoot TS, shipped 10/98 per 1999 Disk / Trend Report – Rigid Disk Drives
^ The Quantum Bigfoot TS used a maximum of 3 platters, other earlier and lower capacity product used to 4 platters in a 5.25 HH form factor, eg Micro Science HH1090 circa 1989.
^ Murphy, David. "Western Digital launches world's first 2TB hard drive". PC World. http://www.pcworld.com/article/158374/Western_Digital_Launches_WorldFirst_2TB_Hard_Drive.html?tk=rss_news. 27/01/2009 fetched.
^ "Seagate PATA (EIDE) desktop hard drives." http://www.seagate.com/ww/v/index.jsp?name=DB35_Series_7200.3-UltraATA-100_750GB-8_ST3750840ACE&vgnextoid=6828cd2655bfd010VgnVCM100000dd04090aRCRD&locale=en-US.
^ "WD ships industry's first 2.5-inch hard drive 1 TB." http://www.engadget.com/2009/07/27/wd-ships-industrys-first-2-5-inch-1tb-hard-drive/.
^ "WD Scorpio Blue 320 GB PATA hard drives." http://www.wdc.com/cN/products/products.asp?DriveID=599.
^ "Toshiba Storage Solutions – MK3233GSG. Http://www.toshiba.co.jp/about/press/2009_11/pr0501.htm.
^ "Toshiba Storage Solutions – MK2431GAH. http://www.storage.toshiba.eu/index.php?id=87&pid=242&sid=7.
^ "SDK Launch Shipments of 1.3-inch PMR technology-based HD Media". Sdk.co.jp. 10/01/2008. http://www.sdk.co.jp/aa/english/news/2008/aanw_08_0812.html. 03/13/2009 fetched.
^ "Toshiba 'world's smallest hard drive". Toshibastorage.com. http://www.toshibastorage.com/main.aspx?Path=StorageSolutions/0.85-inchHardDiskDrives/MK4001MTD/MK4001MTDSpecifications. 03/13/2009 fetched.
^ "One Drive, Multiple Applications – Tom's Hardware: New Drive WD Raptor is a bird of prey". Tomshardware.com. 04/21/2008. http://www.tomshardware.com/reviews/HDD-SATA-VelociRaptor 0.1914-6. html. 03/13/2009 fetched.
^ "Seagate Introduces World's thinnest 2.5-inch hard Slim Drive For Laptops ". Physorg.com. 15/12/2009. Http: / / www.physorg.com/news180118264.html. Retrieved 12/15/2009.
^ 1.3 HDD product specification, Samsung, 2008
^ 0.85-inch HDD by Toshiba is set to multi-gigabyte capacities to bring small, powerful digital products, Toshiba press release, January 8, 2004
^ Toshiba Guinness World Records Book with the world's smallest hard drive, Toshiba press release, March 16, 2004
^ Flash price fall shakes HDD market, EETimes Asia, August 1, 2007.
^ In 2008, Samsung introduced a 1.3-inch HDD SpinPoint A1, but in March 2009 the family was known as End of Life new products and new 1.3-inch models are not available in this size.
^ "WD Caviar Blue: Drive Specification (SATA 250 750 GB)" (PDF). Document Library. Western Digital. June 2008. p. 2. http://wdc.com/en/library/sata/2879-701277.pdf. 27/06/2009 fetched.
^ Momentus 5400.5 SATA 3Gb / s 320-GB hard drive
^ "Reed Solomon Codes – Introduction "
^ Micro House PC Hardware Library Volume I: Hard Drives, Scott Mueler, Macmillan Computer Publishing
^ Waea.org, Rugged Disk Drives Commercial Airborne Computer Systems
^ Barracuda 7200.10 Serial ATA Product Manual
^ IEEE.org, IEEE Trans. Magn.
^ Pugh et al,. "IBM's 360 and Early 370 Systems", MIT Press, 1991, pp.270
^ "Sony | For Business | VAIO SMB. B2b.sony.com. http://b2b.sony.com/Solutions/lpage.do?page=/vaio_smb/index.html&name=VAIO SMB. 03/13/2009 fetched.
HP.com ^
^ Toshiba HDD Protection measures.
^ "Quake-Catcher Network. http://qcn.stanford.edu/. 090128 qcn.stanford.edu
^ Abcd Eduardo Pinheiro, Wolf-Dietrich Weber and Luiz Andre Barroso (February 2007). Failure Trends in a Large Disk Drive Population. 5th USENIX Conference on File and Storage Technologies (FAST 2007). USENIX Conference on File and Storage Technologies. http://labs.google.com/papers/disk_failures.html. 2008-09-15 retrieved.
^ CNet.com
^ "Everything you know about disks is wrong". storage mojo. February 20, 2007. http://storagemojo.com/?p=383. 2007-08-29 retrieved.
^ "Differences between an enterprise-class HDD and a desktop-class HDD. Synology.com. 09/04/2008. http://www.synology.com/wiki/index.php/Differences_between_an_Enterprise-Class_HDD_and_a_Desktop-Class_HDD. 03/13/2009 fetched.
^ Intel White Paper on Enterprise-class versus desktop-class Hard Drives
^ Apparently the CMI disks suffered from a higher soft error rate than other IBM suppliers (Seagate and Miniscribe), but the bugs in Microsoft's DOS operating system have turned this RECOVER About the Author
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Christian Louboutin ANEMONE Barbie Doll MODEL MUSE Gold Label NEW NRFB MIB No 14 $99.95 |
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2009 BLACK LABEL BARBIE DOLL BASICS NEW MIB $69.94 |
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MIB Silkstone Barbie “The Interview” Gold Label NRFB $79.00 |
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Check, Please Francie Silkstone Barbie Doll Rooted Eyelashes GOLD LABEL MIB NRFB $89.95 |
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BARBIE WIZARD OF OZ WINKIE GUARD WINGED MONKEY DOLLS 2007 PINK LABEL MIB $79.99 |
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Gold Label Barbie Learns to Cook 2006 #K9141 MIB NRFB $89.00 |
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2010 Silkstone Barbie BETTY DRAPER Mad Men Mint in box -Read- Gold Label $71.99 |
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Palm Beach Breeze Silkstone Barbie Fashion Model Doll BFMC GOLD LABEL MIB NRFB $80.99 |
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Versus 2004 Barbie Doll GOLD LABEL MIB NRFB $65.00 |
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MINT IN BOX NRFB CAMPUS SWEET SHOP GOLD LABEL MIDGE ALLAN REPRO FASHIONS ACCESSO $75.00 |
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Turn Back Time Cher for Black Label Barbie Clothing Designed by Bob Mackie MIB $65.00 |
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Silkstone Barbie Chinoiserie Red Moon Gold Label MIB NRFB $59.00 |
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Twilight Bella Swan Barbie Breaking Dawn Pink Label MIB Mattel Canada Variant $49.99 |
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BARBIE CAMPUS SWEETHEART GOLD LABEL SERIES MINT IN BOX $65.00 |
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Barbie Ken 50th 2011 Pink Label Mint in Box Mattel $39.99 |
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James Bond Octopussy Barbie Black Label MIB New $49.99 |
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James Bond Live and Let Die Barbie Black Label MIB New $49.99 |
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BARBIE Doll Blonde hair Zodiac LIBRA pink label MIB $60.15 |
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BARBIE DOLLS OF THE WORLD IMPERIAL RUSSIA PINK LABEL RUSSIAN PRINCESS FIGURE MIB $59.99 |
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Ethereal Princess Barbie Pink Label NRFB MIB $59.99 |
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2006 Gold Label Made For Each Other 1969 Reproduction #1881 Barbie Doll New MIB $59.50 |
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Barbie JOAN JETT DEBBIE HARRY CYNDI LAUPER LADIES of the 80′S MIB PINK LABEL $50.00 |
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Princess of Ancient Mexico Barbie Doll MIB 2004 Pink Label Dolls of the World $55.00 |
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Barbie Collectors Black Label James Bond 007 – OCTOPUSSY Doll MIB $54.99 |
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Barbie Collector Couture Angel Pink Label Doll New MIB $54.00 |
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2005 Cynthia Rowley Barbie Doll GOLD LABEL MIB $45.00 |
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Twilight Bella Swan Barbie Breaking Dawn Pink Label MIB Mattel Hard to Find $34.99 |
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Collect a Sold-Out MIB Pink Label Barbie Elvis Aaron Presley Doll ~eLViS~ COA $52.00 |
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2011 Barbie Collector Pillow Talk Rock Hudson & Doris Day Pink Label MIB NRFB $39.99 |
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Barbie Pink Label Dolls of the World Russia in Winter Dress 2009 MIB $39.99 |
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Birthday Wishes Barbie Silver Label Barbie Collector MIB NRFB $39.99 |
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Birthday Wishes Barbie- 2004-Silver Label- MIB- NEW!! RARE!! C6229 $34.99 |
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MIB BARBIE Grease 30th Anniversary Pink Label Dolls $39.99 |
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MIB BARBIE Batman and Catwoman Pink Label Dolls $39.99 |
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Barbie Munchkins The Wizard of Oz Pink Label NIB MIB $41.99 |
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BARBIE ELVIS NEW/MINT IN BOX PINK LABEL 2011 $39.00 |
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Capricorn Barbie Pink Label NRFB MIB $34.99 |
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2007 Dolls of The World DOTW SUMATRA~INDONESIA BARBIE ~ MIB NRFB Pink Label $44.99 |
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2009 Black Label BARBIE BASICS #04-001 Black Afro-American ~ MIB NRFB Short Hair $44.99 |
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2008 DOTW 50th Anniversary FRANCE – FRENCH CANCAN BARBIE ~ Pink Label ~ MIB NRFB $44.99 |
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MY MELODY Barbie Doll PINK Label NRFB mint MIB Steffie face Model Muse Sanrio $44.95 |
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Birthstone Beauties Barbiie Miss Garnet January Pink Label AA Brand New MIB $34.99 |
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Birthstone Beauties Barbiie Miss Opal October AA Pink Label Brand New MIB $34.99 |
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Birthstone Beauties Barbiie Miss Turquoise December AA Pink Label Brand New MIB $34.99 |
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Barbie – Goldie Hawn Black Label Collectible is MIB Blonde Ambition go-go dancer $43.57 |
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Twilight Saga JACOB Barbie Doll Collection Pink Label MIB RARE $24.95 |
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MIB Pink Label Frank Sinatra Collector Barbie Doll Edition ~ Ol’ Blue Eyes ~ $42.00 |
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BARBIE BASICS BLACK LABEL RED HEAD HAIR DOLL/MODEL NO 3 COLLECTION 001.5 NEW MIB $30.00 |
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I LOVE LUCY DOLL “LUCY TELLS THE TRUTH” BARBIE PINK LABEL MIB BRAND NEW $29.99 |
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Twilight Barbie Pink Label Jane MIB Never Opened. Limited Release Canada Version $24.99 |
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I LOVE LUCY DOLL “LUCY TELLS THE TRUTH” BARBIE PINK LABEL MIB BRAND NEW $26.99 |
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BARBIE COLLECTOR THE FLINTSTONES BARBIE GIFTSET M1211 SILVER LABEL 2008 MIB NRFB $20.49 |
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Jeff Gordon NASCAR Barbie Collector Doll 2006 Pink Label New NRFB MIB Model Muse $37.95 |
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BARBIE HAPPY BIRTHDAY GORGEOUS PINK LABEL 2008 MIB $28.00 |
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Barbie Basics- Black Label Model No. 06 Collection 001 MIB 2009 $27.00 |
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Barbie Basics Black Label Doll Accessory Pack Look No. 01 Collection 001.5 MIB $28.99 |
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2011 Barbie Basics Doll Model 5 Collection 3 Black Label NRFB MIB Swimsuit $24.99 |
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KEN DOLL AS MR SPOCK PINK LABEL BARBIE MIB STAR TREK $32.99 |
