Quantum FIREBALL PLUS AS 10.2 Product Manual page 155

K K K K
KILOBYTE (K) – A unit of measure
10
consisting of 1,024 (2
L L L L
LANDING ZONE – A position inside the
disk's inner cylinder in a non data area
reserved as a place to rest the heads during
the time that power is off. Using this area
prevents the heads from touching the
surface in data areas upon power down,
adding to the data integrity and reliability of
the disk drive.
LATENCY – The period of time during
which the read/write heads are waiting for
the data to rotate into position so that it can
be accessed. Based on a disk rotation speed
of 3,662 rpm, the maximum latency time is
16.4 milliseconds, and the average latency
time is 8.2 milliseconds.
LOGICAL FORMAT – The logical drive
geometry that appears to an AT system
BIOS as defined by the drive tables and
stored in CMOS. With an installation
program like Disk Manager, the drive can be
redefined to any logical parameters
necessary to adapt to the system drive tables.
LOOK AHEAD – The technique of
buffering data into cache RAM by reading
subsequent blocks in advance to anticipate
the next request for data. The look ahead
technique speeds up disk access of
sequential blocks of data.
LOW-LEVEL FORMATTING – Formatting
that creates the sectors on the platter
surfaces so the operating system can access
the required areas for generating the file
structure. Quantum drives are shipped with
the low-level formatting already done.
LOW PROFILE – Describes drives built to
the 3 1/2-inch form factor, which are only 1
inch high.
) bytes.
Quantum Fireball Plus LM 10.2/15.0/20.5/30.0 GB AT
M M M M
MB – See megabyte.
MEDIA – The magnetic film that is
deposited or coated on an aluminum
substrate which is very flat and in the shape
of a disk. The media is overcoated with a
lubricant to prevent damage to the heads or
media during head take off and landing. The
media is where the data is stored inside the
disk in the form of magnetic flux or polarity
changes.
MEGABYTE (MB) – A unit of
measurement equal to 1,024 kilobytes, or
1,048,576 bytes except when referring to
disk storage capacity.
1 MB = 1,000,000 bytes when referring to
disk storage capacity.
See also kilobyte.
MEGAHERTZ – A measurement of
frequency in millions of cycles per second.
MHz – See megahertz.
MICROPROCESSOR – The integrated
circuit chip that performs the bulk of data
processing and controls the operation of all
of the parts of the system. A disk drive also
contains a microprocessor to handle all of
the internal functions of the drive and to
support the embedded controller.
MICROSECOND (µs) – One millionth of a
second (.000001 sec.).
MILLISECOND (ms) – One thousandth of
a second (.001 sec.).
MTBF – Mean Time Between Failure. Used
as a reliability rating to determine the
expected life of the product expressed in
power on hours (POH). There are several
accepted methods for calculating this value
that produce very different results and
generate much confusion in the industry.
When comparing numbers you should first
verify which method was used to calculate
the values.
Glossary
G-5