Quantum FIREBALL PLUS AS 10.2 Product Manual page 151

A A A 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 Quantum 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.
AIRLOCK – A patented Quantum feature
that ensures durable and reliable data
storage. Upon removal of power from the
drive for any reason, the read/write heads
automatically park and lock in a non data
area called the landing zone. AIRLOCK
allows the drive to withstand high levels of
non-operating shock. When power is applied
to the drive, airflow created from the
spinning disks causes the AIRLOCK arm to
swing back and unlock the actuator,
allowing the heads to move from the landing
zone. Upon power down, the AIRLOCK
swings back to the locked position, locking
the heads in the landing zone. A park utility
is not required to park the heads on drives
equipped with AIRLOCK (all Quantum
drives).
ALLOCATION – The process of assigning
particular areas of the disk to particular files.
See also allocation unit.
Quantum Fireball Plus AS 10.2/20.5/30.0/40.0/60.0 GB AT
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 B B 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 low-level
formatting program when the drive is being
installed. Because Quantum disk drive's
defect-management scheme handles all such
flaws automatically, there is no need to
concern yourself with bad track tables.
BIT – Abbreviation for binary digit. A binary
digit may have one of two values—1 or 0.
This contrasts with a decimal digit, which
may have a value from 0 to 9. A bit is one of
the logic 1or logic 0 binary settings that
make up a byte of data. See also byte.
BLOCK – A sector or group of sectors. By
default, a block of data consists of 512 bytes.
GLOSSARY GLOSSARY GLOSSARY GLOSSARY
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