| Word |
Description |
|
|
| Access |
Retrieval of data from or transfer of data into a storage device or area such as RAM or a register. |
| Access Time |
The amount of time, including seek time, latency and controller time, needed for a storage device to retrieve information. |
| Active Partition |
The partition of the drive that contains the operating system. If the drive has multiple partitions, only the primary partition can be made active. A hard drive can have only one active partition. |
| Active Termination |
One or more voltage regulators that produce termination voltage. The voltage regulator(s) drive a constant voltage along the bus to ensure that the data signal stays constant and strong over the entire length of the bus. The result is increased data integrity and reliability. |
| Actuator |
A mechanical assembly that positions the read/write head over the appropriate track. |
| Actuator Arm |
The part of the actuator assembly that includes the positioning arm and the read/write heads. |
| Adaptive Caching |
A feature of hard disk drives that enables them to improve performance and throughput by adapting to the application being run. |
| Address |
In the hard drive industry, there are several types of addresses; an address may refer to that of a drive, called a unit address; radial position, called a cylinder address; or circumferential position, referred to as a sector address. |
| AFR |
Annualized Failure Rate. |
| Allocation |
The method DOS uses to assign a specific area of the hard drive to a given file. (See also cluster.) |
| American National Standards Institute (ANSI) |
A governmental body of the United States responsible for approving US standards in many areas, including computers and communications. ANSI is a member of the International Standards Organization (ISO). |
| Arbitrated Loop |
Fibre channel topology where two or more ports can interconnect but only two ports can communicate at the same time. |
| Arbitration |
The act of determining which command, device, or communication protocol controls the operating environment. |
| Areal Density |
The number of bits of data that can be recorded onto the surface of a disk or platter usually measured in square inches. The areal density is calculated by multiplying the bit density (BPI - Bits Per Inch) by the track density (TPI - Tracks Per Inch). |
| Asynchronous Transmission |
Each byte of information is synchronized individually through the use of request and acknowledge signals. |
| AT Bus Attachment (ATA-4) |
The interface defined by IBM for the original AT disk controller. |
| ATA (Advanced Technology Attachment) |
A disk drive interface standard for IDE (Integrated Drive Electronics). A standard for storage devices that lets them be treated as if they were hard drives on the system. Any ATA compatible media can be read by any ATA device. |
| Auto Defect Retirement |
If the drive finds defective sectors during reads or writes, they are automatically mapped out and relocated. |
| Auto Park |
Turning off the drive power causes the drive to move the read/write heads to a safe non-data landing zone and lock them in place. |
| Average Access Time |
The average length of time a drive takes to perform seeks, usually measured with 1/3 stroke. |
| Average Seek Time |
Length of time it takes the drive to move the read/write heads to a safe non-data landing zone and lock them in place. |
| Backup |
To make a copy of a file, group of files, or the entire contents of a hard disk, either for archiving purposes or for safeguarding valuable files from loss should the active copy be damaged or destroyed. |
| Bad Block |
A disk sector that can no longer be used for data storage, usually due to media damage or imperfections. |
| Bandwidth |
The amount of data that can be sent over a given circuit. See also buffer bandwidth. |
| BIOS (Basic input/output system) |
A program or set of programs that control the basic functions of the computer. |
| Bit |
An abbreviation for a binary digit which can be either 0 or 1. A bit is the basic data unit of all digital computers. It is usually part of a data byte, or data word; however, a single bit can be used to control or read logic ON/OFF functions. A bit is a single digit in a binary number. Bits are the basic unit of information capacity on a computer storage device. Eight bits equal one byte. |
| Bit density |
Expressed as bits per inch (BPI), the number of bits that can be written onto one inch of track on a disk surface. |
| Block |
A group of bytes handled, stored, and accessed as a logical data unit, such as an individual file record. A block in UNIX workstation environments is the smallest contiguous area that can be allocated for the storage of data. (Note: A different definition of the term is used when referring to the physical configuration of a hard drive.) |
| Boot |
To start or restart your computer; loading the operating system. |
| BPI |
Bits per inch. Indicates the density of information on a hard drive. See also bit density. |
| Buffer |
A temporary data storage area used to make up for a difference in data transfer rates and/or data processing rates between sender and receiver. For example, a printer buffer copies data from the computer and holds it until the printer is ready to print it. |
| Buffer Bandwidth |
The speed of transferring data to or from the buffer. |
| Bunny Suit |
A head-to-toe garment worn by personnel in a Clean Room. |
| Burst Mode Transfer Rate |
The transfer rate into the buffer RAM of the hard disk. This rate does not factor in delays due to latencies or host delays. See also transfer rate. |
| Bus |
A term used for an electronic device in which a number of elements are wired together with a single wire in such way that all the elements can use the same wire to transmit information to other devices on it. Buses are used internally in computers and used to attach computers to peripherals. Only devices addressed by the signals pay attention to them; the others discard the signals. |
| Byte |
A sequence of eight binary digits or bits regarded to be a unit or binary word. The storage capacity of a disk drive is commonly measured in megabytes, which is the total number of storable bits divided by eight million. |
| Cable Select (CSEL) |
An alternative option which can be used in place of setting Master/Slave jumpers in the designation of drives in a dual drive configuration. Master/Slave designation is based on the position of the drives relative to the cable. Special cabling is required by the system manufacturer to selectively ground the CSEL signal on one of the IDE cable connectors. For example, when one of the drives is connected to the grounded CSEL conductor, it configures itself as the Master. When the second drive is connected to the other connector, on which CSEL is not grounded, it becomes the slave. This eliminates the need for unique jumpering configurations between the Master and Slave drives. |
| Cache |
High-speed RAM used as a buffer between the CPU and a hard drive. The cache retains recently accessed information to speed up subsequent accesses to the same data. When data is read from or written to disk, a copy is saved in the cache, along with the associated disk address. The cache monitors the addresses of subsequent read operations to see if the required data is already in the cache. If it is, the drive returns the data immediately. If it is not in the cache, then it is fetched from the disk and saved in the cache. |
| Capacity |
The amount of information, measured in bytes, that can be stored on a hard drive. Also known as storage capacity. |
| Central Processing Unit (CPU) |
The main processing chip of a computer. The CPU interprets and executes the actual computing tasks, and has the ability to transfer information to and from other resources over the computer's main data-transfer path, the bus. |
| Channel |
A connection or socket on the motherboard or controller card. A motherboard may have one or two channels (primary and secondary). If your motherboard has only one channel, you may need to add a controller card to create a secondary channel. |
| Channel Assembly |
In the computer industry, the final assembly of a system by a distributor or reseller from kits provided by the manufacturer and from components shipped directly to the assembler by subsystem makers. |
| Clean Room |
An environmentally controlled, dust-free, assembly or repair facility in which hard drives are assembled or opened for internal servicing. |
| Cluster |
A hard disk term that refers to a group of sectors. A cluster is considered an allocation unit. At least one cluster is allocated to each file, regardless of the file's size, that is stored in the DOS environment. The cluster size increases with the partition size determined during formatting. With a 1024 MB partition, the cluster size is 32 KB. Each file stored consumes 32 KB of storage space, no matter how small the file. Create multiple, smaller partitions to avoid wasting space on small files. (This definition applies to FAT16). |
| CMOS Setup |
A program supplied in most systems that allows you to configure internal and external devices. |
| Command Aging |
A SCSI feature that prevents the command reordering algorithm from keeping I/O processes waiting in the command queue for extended periods of time. |
| Command Queuing |
A feature that enables the drive to receive I/O processes from one or more initiators and execute them in an optimum sequence. |
| Command Reordering |
A feature that allows the drive to reorder I/O processes in the command queue, which results in minimizing the seek time and rotational latency and thus increases throughput. |
| Controller |
A device that transfers information between the computer and peripheral devices. The controller (or control unit) acts as a traffic manager. See also disk controller, interface controller, and disk drive controller. |
| Controller Card |
An adapter with the control electronics for one or more hard drives. Usually installed in a bus slot in the computer. |
| Correctable Error |
An error that the drive can correct by using Error Detection and Correction schemes. |
| Customer Configuration Code (CCC) |
A firmware revision tracking code that defines a major product change. This number increments as form, fit or function changes are implemented. The CCC code guarantees that the correct revision of drive product is provided to the customer. |
| Cyclic Redundancy Check (CRC) |
Data stored or transmitted with data to detect corruption. By calculating the CRC data and comparing it to the original data sent, the receiver can detect some types of transmission errors. |
| Cylinder |
The cylindrical surface formed by identical track numbers on vertically stacked disks. |
| Cylinder, Head, Sector (CHS) Addressing |
A method of referencing the sectors on a drive as a collection of unique cylinder, head and sector addresses. Each block on the drive will have a unique cylinder, head and sector address. |
| Data Recovery |
Data recovery is the procedure used to recover data from a variety of media and operating systems that has been lost by either hardware failure, human error, software bugs, a virus or a natural disaster. |
| Data Synchronizer |
An electronic circuit that uses a clock signal to synchronize data to facilitate interpretation. |
| Data Transfer Rate |
The rate that digital data transfers from one point to another, expressed in bits per second or bytes per second. Data Transfer Rate to Disk: The internal disk transfer rate in Mbits per second.Data Transfer Rate from the Buffer to the Host: Based on the transfer of buffered data in MB per second. |
| Database |
A collection of data stored on a computer system medium, such as a hard drive, CD-ROM, etc., that can be used for more than one purpose. |
| Dedicated Landing Zone |
The designated radial zone of the disk, usually at the inner portion of the disk, where the heads are stored to avoid contact with the data cylinders when power to the drive is off. |
| Defect Free |
A term used to describe recording surfaces that have no detectable defects. |
| Defect Management |
A general methodology of eliminating data errors on a recording surface by mapping out known defects on the media. The defective areas are rendered inaccessible, so that when information is written to the disk, it is stored to non-defective locations on the disk. |
| Differential SCSI |
An electrical signal configuration which uses pairs of lines for data transfer. Used primarily in applications requiring long cable lengths of up to 82 feet (25 meters). |
| Direct Memory Access (DMA) |
A process for transferring data directly to and from main memory, without passing through the CPU. DMA improves speed and efficiency by allowing the system to continue CPU processing even while it is transferring data to/from the hard drive. |
| Directory |
A list of file names and locations of files on a disk. |
| Disk |
A rigid platter, usually constructed of aluminum or mylar, with a magnetic surface that allows the recording of data, that is stored inside the drive. |
| Disk Controller |
The chip or circuit that controls the transfer of data between the disk and buffer. (See also disk drive controller and interface controller). |
| Disk Drive |
The motor that actually rotates the disk, plus the read/write heads and mechanisms. |
| Disk Drive Controller |
The hard disk drive controller electronics which include the disk controller and the interface controller. (See also disk controller and interface controller.) |
| Disk Operating System (DOS) |
The computer program that controls the organization of data, files and processes on the computer. |
| Disk Transfer Rate |
Speed at which data transfers to and from the disk media (actual disk platter); a function of the recording frequency. Typical units are bits per second (BPS), or bytes per second. Hard drives have an increasing range of disk transfer rates from the inner diameter to the outer diameter of the disk. |
| Distribution Channel |
Electronics distributors and certain retail chains that deliver electronic goods to end users through value-added resellers and some retail stores. |
| EIDE (Enhanced Integrated Drive Electronics) |
The primary interface used by desktop PCs to handle communication between hard drives and the central processing unit. The equivalent interface system in most enterprise systems is SCSI. |
| Embedded Servo Control |
The embedded servo control design generates accurate feedback information to the head position servo system without requiring a full data surface (which is required with a dedicated servo control method) because servo control data is stored on every surface. |
| Encoding |
The process of modifying data patterns prior to writing them on the disk surface. |
| Enterprise |
The series of computers employed largely in high-volume and multi-user environments such as servers or networking applications; may include single-user workstations required in demanding design, engineering and audio/visual applications. |
| Error Correction Code (ECC) |
A mathematical algorithm that detects and corrects errors in a data field. |
| Error Log |
A record that contains error information. |
| Error Rate |
The number of errors of a given type that occur when reading a specified number of bits. |
| Extended Partition |
You can create multiple partitions on a hard disk, one primary partition and one or more extended partition(s). Operating system files must reside on the primary partition. An extended partition is a partition where non-system files (files other than DOS or operating system files) can be stored on a disk. You can also create logical drives on the extended partition. |
| FAT (File Allocation Table) |
A data table stored at the beginning of each partition on the disk that is used by the operating system to determine which sectors are allocated to each file and in what order. |
| Fdisk |
A software utility used to partition a hard drive. This utility is included with DOS and Windows 95 operating systems. |
| Fetch |
The process of retrieving data. |
| Fibre Channel (FC) |
The general name given to an integrated set of standards being developed by an ANSI-approved X3 group. This set of standards defines new protocols for flexible information transfer. Fibre channel supports three topologies: point-to-point, arbitrated loop, and fabric. |
| Fibre Channel Arbitrated Loop (FC-AL) |
A subset of fibre channel network systems interconnection. A serial storage interface designed to meet the needs of high-end applications. |
| Firewire |
FireWire (also referred to as IEEE1394 High Performance Serial Bus) is a very fast external bus that supports data transfer rates of up to 800 Mbps. It is similar to USB. It preceded the development of USB when it was originally created in 1995 by Apple. FireWire devices can be connected and disconnected any time, even with the power on. When a new FireWire device is connected to a computer, the operating system automatically detects it and prompts for the driver disk. |
| Firmware |
Permanent instructions and data programmed directly into the circuitry of read-onlymemory for controlling the operation of the computer. |
| FIT (Functional Integrity Testing) |
A suite of tests on hard drive products to ensure compatibility with different hosts, operating systems, adapters, application programs, and peripherals. This testing must be performed before the product can be released to manufacturing. |
| Flow Control |
In PIO transfers, the ability of an EIDE drive to control the speed at which the host transfers data to or from the drive by using the IORDY signal. The host temporarily stops transferring data whenever the drive deasserts the IORDY signal. When the drive reasserts the IORDY signal, the host continues the data transfer. |
| Form Factor |
The industry standard that defines the physical and external dimensions of a particular device. |
| Format |
A process that prepares a hard drive to store data. Low-level formatting sets up the locations of sectors so user data can be stored in them. Most hard drives are low-level formatted at the factory and therefore do not need to be low-level formatted by the end user. You need to perform a high-level format (with EZ-Drive or the Format command) on your new hard drive before you can use it. Formatting erases all the information on a hard drive and it sets up the file system needed for storing and retrieving files. |
| Formatted Capacity |
The actual capacity available to store data in a mass storage device. The formatted capacity is the gross capacity minus the capacity taken up by the overhead data required for formatting the media. |
| Full-Duplex |
A communication protocol that permits simultaneous transmission in both directions. |
| GB (Gigabyte) |
One gigabyte is 1,000,000,000 (one billion) bytes or 1000 (one thousand) Megabytes. |
| Half-Duplex |
A communications protocol that permits transmission in both directions but in only one direction at a time. |
| Half-height Drives |
Standard 3.5-inch hard drives are available in heights of 1.0-inch and 1.6-inches. Half-height drives measure 1.6-inches in height. |
| Hard Disk |
A mass storage device that transfers data between the computer's memory and the disk storage media. Hard disks are rotating, rigid, magnetic storage disks. |
| Hard Drive |
An electromechanical device used for information storage and retrieval, incorporating one or more rotating disks on which data is recorded, stored and read magnetically. |
| Hard Drive Industry |
The combined manufacturers of hard drives. In the United States, the industry is led by IBM, Maxtor, Seagate, Quantum and Western Digital. |
| Hard Error |
An error that is repeatable every time the same area on a disk is accessed. |
| Hard Sectored |
A technique that uses a digital signal to indicate the beginning of a sector on a track. |
| Head |
The minute electromagnetic coil and metal pole which write and read back magnetic patterns on the disk. Also known as a read/write head. A drive with several disk surfaces or platters will have a separate head for each data surface. See also MR Head. |
| Head Actuator |
A motor that moves the head stack assembly in a hard drive to align read/write heads with magnetic tracks on the disks. |
| Head Crash |
Refers to the damage incurred to a read/write head when the head comes into contact with the disk surface. A head crash might be caused by severe shock, dust, fingerprints, or smoke, and can cause damage to the surface of the disk and/or the head. |
| Head Disk Assembly (HDA) |
The mechanical components of a hard drive, including the disks, heads, spindle motor and actuator. |
| Head Loading Zone |
An area on the disk specifically reserved for the heads to use when taking off or landing when power to the drive is turned on or off. No data storage occurs in the head loading zone. |
| Head Stack Assembly |
The electromechanical mechanism containing read/write heads and their supporting devices. |
| Headerless Format |
The lack of a header or ID fields (track format). This enables greater format efficiency and increased user capacity. |
| High-end Market |
The enterprise market. |
| High-Level Format |
A high-level format must be performed (with EZ-Drive or the Format command) on a new hard drive (in most cases) before you can use it. Formatting erases all the information on a hard drive and it sets up the file system needed for storing and retrieving files. |
| Host |
The computer that other computers and peripherals connect to. See also initiator. |
| Host Adapter |
A plug-in board that acts as the interface between a computer system bus and the disk drive. |
| Host Interface |
The point at which the host and the drive are connected to each other. |
| Host Transfer Rate |
Speed at which the host computer can transfer data across the SCSI interface; or, the speed at which the host computer can transfer data across the EIDE interface. Processor Input/Output (PIO) modes and Direct Memory Access (DMA) modes are defined in the ATA-4 industry specifications for the EIDE interface. |
| IDE (Integrated Drive Electronics) |
A type of drive where the interface controller electronics are incorporated into the design of the hard drive rather than as a separate controller. |
| Index Pulse Signal |
A digital pulse signal indicating the beginning of a disk revolution. An embedded servo pattern or other prerecorded information is present on the disk following index. |
| Initialization |
See low-level formatting. |
| Initiator |
A device in control of the SCSI bus that sends commands to a target. Most SCSI devices have a fixed role as an initiator or a target; however, some devices can assume both roles. |
| Input |
The incoming data that the computer processes, such as commands issued by the user. |
| Input/output (I/O) |
An operation or device that allows input and output. |
| Interface |
A hardware or software protocol that handles the exchange of data between the device and the computer; the most common ones are AT (also known as IDE) and SCSI. (See AT and SCSI.) |
| Storage Capacity |
The amount of data that can be stored on a hard drive. |
| Sub-1000 PC |
The series of personal computers being designed for sale at prices at or below $1,000 each. |
| Subsystem |
A secondary or component part of a system, as a hard drive is a subsystem of a personal computer. |
| Surface |
The top or the bottom side of a platter coated with a magnetic material required to record data. A platter may use one or both surfaces to store data. |
| Synchronous Transmission |
Transmission in which the sending and receiving devices operate continuously at the same frequency and are held in a desired phase relationship by a correction device. |
| System Files |
The files needed to run an operating system. |
| System Integrator |
An independent professional who specifies and provides the necessary combinations of hardware and software in response to an end user's needs. |
| Tagged Queuing |
The ability of the drive to receive multiple I/O processes from each initiator. |
| Task File |
The set of I/O Host Interface Registers used to transfer status, commands, and data between the host and the drive for the EIDE interface. |
| Thin Client Architecture |
A computer system in which data is stored centrally, with only limited storage capacity at the various points of use. |
| Thin Film |
A type of coating deposited on a flat surface through a photolithographic process. Thin film is used on disk platters and read/write heads, as well as on the write element of MR heads. |
| Thin-Film Inductive Head (TFI) |
A head technology that uses a thin-film inductive element to read and write data bits on the magnetic surface of the disk. |
| Time-to-Capacity |
Getting to market first with the next highest capacity hard drive. |
| Time-to-Market |
The time it takes to bring a product from concept to market. Generally first-to-market is the desired time-to-market goal. |
| Time-to-Quality |
The time required to bring a new product to market with the best possible level of quality and reliability. |
| Time-to-Volume |
The time required to begin producing a new product in sufficiently high volume to fill commercial requirements. |
| TPI (Tracks per inch) |
The number of tracks written within each inch of the disk's surfaces, used to measure how closely the tracks are packed on a disk surface. Also known as track density. |
| Track |
A concentric magnetic circle pattern on a disk surface used for storing and reading data. |
| Track-to-track Seek Time |
The time that elapses when the read/write heads move from one track to an adjacent track. |
| Transfer Rate |
The rate at which the hard drive sends and receives data from the controller. Processing, head switches, and seeks are all figured into the transfer rate in order to accurately portray drive performance. The burst mode transfer rate is separate from transfer rate, as it refers only to the transfer of data into RAM. |
| Translating BIOS |
A system BIOS that allows access to EIDE drives larger than 528 MB. |
| Ultra DMA/33 |
A high-speed host data transfer feature that transfers data at 33.3 MB per second. |
| Ultra SCSI |
Provides 20 MB/s transfers over an 8-bit bus or 40 MB/s transfers over a 16-bit Wide SCSI bus. Also known as Fast-20 SCSI, this feature is most commonly found in SCSI-3 drives. |
| Un-correctable Error |
An error that cannot be overcome using Error Detection and Correction. |
| Unformatted Capacity |
The total number of usable bytes on a disk, including the space that is required to record location, boundary definitions, and servo data. (See also formatted capacity.) |
| Universal Serial Bus (USB) |
A serial bus with a bandwidth of 1.5 megabits per second (Mbps) for connecting peripherals to a microcomputer. USB can connect up to 127 peripherals, such as external CD-ROM drives, printers, modems, mice, and keyboards, to the system through a single, general-purpose port. This is accomplished by daisy chaining peripherals together. USB supports hot plugging and multiple data streams. |
| Unrecoverable Error |
A read error that cannot be overcome by an ECC scheme or by rereading the data when host retries are enabled. |
| Untagged Queuing |
The ability of the drive to receive a maximum of one I/O process from each initiator. |
| Upgrade |
In hard drives, the replacement of a hard drive with one offering greatercapacity or performance, or both. |
| Virus Scanner |
Software that is used to scan for and eradicate computer viruses, worms, and Trojan horses. |
| Viterbi Detection |
An algorithm used in read channel technology that detects an entire sequence of data bits at a time and determines the most likely sequence of data bits by comparing actual sequence of data bit samples with sequences of possible data bit sample to accurately detect that data written to disk. |
| Voice Coil |
An actuator motor; the force of the magnetic rotary voice coil produces a movement of the head that is proportionate to the force exerted by the coil. |
| Volume |
A portion of a physical disk that functions as though it were a physically separate disk. . |
| Winchester Disk |
Former code name for an early IBM hard disk model, sometimes still used to refer to the technology and design of most traditional hard drives. |
| Windows |
Microsoft's series of operating systems for personal computers. Currently popular versions are Windows 95 and Windows 98. |
| Word |
Two bytes that are processed together in a single operation. |
| Workstation |
A personal computer with exceptional capacity and performance capabilities for use mainly in engineering, design and audiovisual applications demanding immediate access to data and the ability to manipulate it in technically sophisticated ways. |
| Write |
The recording of flux reversals onto the magnetic surface of a disk. |
| Write Cache |
High speed RAM used to buffer data transfer from the host to the hard drive. |
| Write Verify |
Immediately after writing data to the disk, a drive with the Write Verify feature will verify that it can read the data it just wrote to the disk to ensure that it will be able to retrieve it later. If the drive is unable to read the data, it writes it to another area of the disk, where it attempts to write verify it again. |
| Zoned Recording |
Increases the number of sectors on the outer tracks of the drive since the circumference of the outside tracks is greater. This type of recording affords more disk capacity because there can be more sectors on the larger outer tracks than would be possible if the number of sectors per track were constant for the whole drive. |
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