Glossary
A
ACCESS – (v) Read, write, or update information on some storage medium, such as a disk. (n) One of these operations.
ACCESS TIME – The interval between the time a request for data is made by the system and the time the data is available from the drive. Access time includes the actual seek time, rotational latency, and command processing overhead time. See also seek, rotational latency, and overhead.
ACTUATOR – Also known as the positioner. The internal mechanism that moves the read/write head to the proper track. The Maxtor actuator consists of a rotary voice coil and the head mounting arms. One end of each head mounting arm attaches to the rotor with the read/write heads attached at the opposite end of each arm. As current is applied to the rotor, it rotates, positioning the heads over the desired cylinder on the media.
ALLOCATION – The process of assigning particular areas of the disk to particular files. See also allocation unit.
ALLOCATION UNIT – An allocation unit, also known as a cluster, is a group of sectors on the disk that can be reserved for the use of a particular file.
AVERAGE SEEK TIME – The average time it takes for the read/write head to move to a specific location. To compute the average seek time, you divide the time it takes to complete a large number of random seeks all over the disk by the number of seeks performed.
B
BACKUP – A copy of a file, directory, or volume on a separate storage device from the original, for the purpose of retrieval in case the original is accidentally erased, damaged, or destroyed.
BAD BLOCK – A block (usually the size of a sector) that cannot reliably hold data because of a media flaw or damaged format markings.
BAD TRACK TABLE – A label affixed to the casing of a hard disk drive that tells which tracks are flawed and cannot hold data. The listing is typed into the
BIT – Abbreviation for binary digit. A binary digit may have one of two
BLOCK – A sector or group of sectors.
BPI – Abbreviation for bits per inch. A measure of how densely information is packed on a storage medium. Flux changes per inch is also a term commonly used in describing storage density on a magnetic surface.
BUFFER – An area of RAM reserved for temporary storage of data that is waiting to be sent to a device that is not yet ready to receive it. The data is usually on its way to or from the disk drive or some other peripheral device.
BUS – The part of a chip, circuit board, or interface designed to send and receive data.
BYTE – The basic unit of computer memory, large enough to hold one character of alphanumeric data. Comprised of eight bits. See also bit.
C
CACHE –
CAPACITY – The amount of information that can be stored on a disk drive. The data is stored in bytes, and capacity is usually expressed in megabytes.
CDB – Command Descriptor Block. The SCSI structure used to communicate requests from an initiator (system) to a target (drive).
CLEAN ROOM – An environmentally controlled
CLUSTER – A group of sectors on a disk drive that is addressed as one logical unit by the operating system.
CONTROLLER – Short form of disk controller. The chip or complete circuit that translates computer data and commands.
CONTROLLER CARD – An adapter holding the control electronics for one or more hard disks, usually installed in a slot in the computer.
CPU – Acronym for Central Processing Unit. The microprocessor chip that performs the bulk of data processing in a computer.
Maxtor DiamondMax 17 |
