
Glossary
182 New Template
peak transfer rate The maximum speed with which information
moves inside a tape drive or between drive and host. Usually
measured in megabytes per second.
performance A measure of the speed of the drive during normal
operation. Factors affecting performance are seek times,
transfer rate, and command overhead.
peripheral A device added to a system as a complement to the basic
central processing unit (CPU), such as a disk drive, tape drive, or
printer.
POH Power-on Hours. The unit of
measurement for mean time between failure (MTBF), expressed
as the number of hours that the drive is powered on. See MTBF.
POST Power-on Self Test. Diagnostics programs, loaded automatically
by the BIOS, that perform basic tests on the major system
components, such as memory, cartridge and magazine
information. If no problems are detected during POST, the
system continues the start-up process.
PRML See Partial Response, Maximum Likelihood.
Q QIC Quarter Inch Cartridge. A tape storage subsystem that uses
0.25 inch (6.35 mm) wide media.
R RAM Random Access Memory. an integrated circuit memory chip that
allows information to be stored and retrieved by a
microprocessor or controller. The information can be stored or
accessed in any order, and all storage locations are equally
accessible.
RAIT Redundant Array of Independent Tape Drives
random access The ability to directly locate any piece of data without
having to read everything in memory or on disk.
read after write A mode of operation that has the computer read
back each data block immediately after it is written on the tape,
checking that the data read back is the same as recorded.
read/write head The mechanism by which data is recorded onto
magnetic media in a tape drive system. See read after write.
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