Volume Serial Number Editor Volume Serial Number Editor is a tool to change the hard drive volume serial number (XXXX-XXXX) assigned by the Operating System.

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Hard disk drive - Wikipedia. Hard disk drive. Internals of a 2. SATA hard disk drive. Date invented. 24 December 1. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. HDDs are a type of non- volatile storage, retaining stored data even when powered off. Continuously improved, HDDs have maintained this position into the modern era of servers and personal computers.

More than 2. 00 companies have produced HDDs historically, though after extensive industry consolidation most current units are manufactured by Seagate, Toshiba, and Western Digital. HDD unit shipments and sales revenues are declining, though production (exabytes per year) is growing. Flash memory has a growing share of the market for secondary storage, in the form of solid- state drives (SSDs). SSDs have higher data- transfer rates, higher areal storage density, better reliability.

Capacity is specified in unit prefixes corresponding to powers of 1. TB) drive has a capacity of 1,0. GB; where 1 gigabyte = 1 billion bytes). Typically, some of an HDD's capacity is unavailable to the user because it is used by the file system and the computer operating system, and possibly inbuilt redundancy for error correction and recovery. Performance is specified by the time required to move the heads to a track or cylinder (average access time) plus the time it takes for the desired sector to move under the head (average latency, which is a function of the physical rotational speed in revolutions per minute), and finally the speed at which the data is transmitted (data rate). The two most common form factors for modern HDDs are 3. HDDs are connected to systems by standard interface cables such as PATA (Parallel ATA), SATA (Serial ATA), USB or SAS (Serial attached SCSI) cables.

History. The first IBM drive, the 3. RAMAC in 1. 95. 6, was approximately the size of two medium- sized refrigerators and stored five million six- bit characters (3. Cylinder- mode read/write operations were supported, and the heads flew about 2. Motion of the head array depended upon a binary adder system of hydraulic actuators which assured repeatable positioning. The 1. 30. 1 cabinet was about the size of three home refrigerators placed side by side, storing the equivalent of about 2.

Access time was about a quarter of a second. Also in 1. 96. 2, IBM introduced the model 1. Users could buy additional packs and interchange them as needed, much like reels of magnetic tape. Later models of removable pack drives, from IBM and others, became the norm in most computer installations and reached capacities of 3. Non- removable HDDs were called .

IBM 2. 30. 5 in 1. Its primary distinguishing feature was that the disk heads were not withdrawn completely from the stack of disk platters when the drive was powered down. Instead, the heads were allowed to . This greatly reduced the cost of the head actuator mechanism, but precluded removing just the disks from the drive as was done with the disk packs of the day. Instead, the first models of . A few years later, designers were exploring the possibility that physically smaller platters might offer advantages. Drives with non- removable eight- inch platters appeared, and then drives that used a 5 1.

The latter were primarily intended for the then- fledgling personal computer (PC) market. As the 1. 98. 0s began, HDDs were a rare and very expensive additional feature in PCs, but by the late 1. Most HDDs in the early 1.

PC end users as an external, add- on subsystem. The subsystem was not sold under the drive manufacturer's name but under the subsystem manufacturer's name such as Corvus Systems and Tallgrass Technologies, or under the PC system manufacturer's name such as the Apple Pro. File. The IBM PC/XT in 1. MB HDD, and soon thereafter internal HDDs proliferated on personal computers.

External HDDs remained popular for much longer on the Apple Macintosh. Many Macintosh computers made between 1.

SCSI port on the back, making external expansion simple. Older compact Macintosh computers did not have user- accessible hard drive bays (indeed, the Macintosh 1. K, Macintosh 5. 12.

K, and Macintosh Plus did not feature a hard drive bay at all), so on those models external SCSI disks were the only reasonable option for expanding upon any internal storage. The 2. 01. 1 Thailand floods damaged the manufacturing plants and impacted hard disk drive cost adversely between 2.

At the same time, market application expanded from mainframe computers of the late 1. Technology. Sequential changes in the direction of magnetization represent binary data bits. The data is read from the disk by detecting the transitions in magnetization. User data is encoded using an encoding scheme, such as run- length limited encoding. The platters are made from a non- magnetic material, usually aluminum alloy, glass, or ceramic, and are coated with a shallow layer of magnetic material typically 1. The read- and- write head is used to detect and modify the magnetization of the material passing immediately under it. In modern drives, there is one head for each magnetic platter surface on the spindle, mounted on a common arm.

An actuator arm (or access arm) moves the heads on an arc (roughly radially) across the platters as they spin, allowing each head to access almost the entire surface of the platter as it spins. The arm is moved using a voice coil actuator or in some older designs a stepper motor. Early hard disk drives wrote data at some constant bits per second, resulting in all tracks having the same amount of data per track but modern drives (since the 1. In modern drives, the small size of the magnetic regions creates the danger that their magnetic state might be lost because of thermal effects, thermally induced magnetic instability which is commonly known as the . To counter this, the platters are coated with two parallel magnetic layers, separated by a 3- atom layer of the non- magnetic element ruthenium, and the two layers are magnetized in opposite orientation, thus reinforcing each other. That so- called exchange spring media, also known as exchange coupled composite media, allows good writability due to the write- assist nature of the soft layer.

However, the thermal stability is determined only by the hardest layer and not influenced by the soft layer. Orange stripe along the side of the arm is thin printed- circuit cable, spindle bearing is in the center and the actuator is in the upper left. A typical HDD has two electric motors; a spindle motor that spins the disks and an actuator (motor) that positions the read/write head assembly across the spinning disks. The disk motor has an external rotor attached to the disks; the stator windings are fixed in place. Opposite the actuator at the end of the head support arm is the read- write head; thin printed- circuit cables connect the read- write heads to amplifier electronics mounted at the pivot of the actuator.

The head support arm is very light, but also stiff; in modern drives, acceleration at the head reaches 5. A metal plate supports a squat neodymium- iron- boron (NIB) high- flux magnet. Beneath this plate is the moving coil, often referred to as the voice coil by analogy to the coil in loudspeakers, which is attached to the actuator hub, and beneath that is a second NIB magnet, mounted on the bottom plate of the motor (some drives have only one magnet). The voice coil itself is shaped rather like an arrowhead, and made of doubly coated copper magnet wire. The inner layer is insulation, and the outer is thermoplastic, which bonds the coil together after it is wound on a form, making it self- supporting.

The portions of the coil along the two sides of the arrowhead (which point to the actuator bearing center) then interact with the magnetic field of the fixed magnet. Windows Xp Professional Mui Swedish Ivy. Current flowing radially outward along one side of the arrowhead and radially inward on the other produces the tangential force.