Seagate DiamondMax 17 Manual page 56

Glossary
CRC – Acronym for Cyclic Redundancy Check. An error
detection code that is recorded within each sector and is
used to see whether parts of a string of data are missing or
erroneous.
CYLINDER – On a disk drive that has more than one
recording surface and heads that move to various tracks, the
group of all tracks located at a given head position. The
number of cylinders times the number of heads equals the
number of tracks per drive.
DATA SEPARATOR – On a disk drive that stores data
and timing information in an encoded form, the circuit that
extracts the data from the combined data and clock signal.
DEDICATED SERVO – A surface separate from the
surface used for data that contains only disk timing and
positioning information and contains no data.
DEFECT MANAGEMENT – A method that is
implemented to ensure long term data integrity. Defect
management eliminates the need for user defect maps. This
is accomplished by scanning the disk drives at the factory for
defective sectors. Defective sectors are deallocated prior to
shipment. In addition, during regular use, the drive
continues to scan and compensate for any new defective
sectors on the disk.
DISK – In general, any circular-shaped data-storage
medium that stores data on the flat surface of the platter. The
most common type of disk is the magnetic disk, which stores
data as magnetic patterns in a metal or metal-oxide coating.
Magnetic disks come in two forms: floppy and hard. Optical
recording is a newer disk technology that gives higher
capacity storage but at slower access times.
DISK CONTROLLER – A plug-in board, or embedded
circuitry on the drive, that passes information to and from
the disk. The Maxtor disk drives all have controllers
embedded on the drive printed-circuit board.
DISKWARE – The program instructions and data stored
on the disk for use by a processor.
DMA – Acronym for direct memory access. A process by
which data moves directly between a disk drive (or other
device) and system memory without passing through the
CPU, thus allowing the system to continue processing other
tasks while the new data is being retrieved.
DRIVE – Short form of disk drive.
DRIVE GEOMETRY – The functional dimensions of a
drive in terms of the number of heads, cylinders, and sectors
per track. See also logical format.
G-2 Maxtor DiamondMax 17 80-160GB Serial ATA Hard Disk Drive
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ECC – Acronym for error correction code. The recording of
extra verifying information encoded along with the disk
data. The controller uses the extra information to check for
data errors, and corrects the errors when possible.
EMBEDDED SERVO – A timing or location signal
placed on the disk's surface on the tracks that also store data.
These signals allow the actuator to fine-tune the position of
the read/write heads.
ENCODING – The protocol by which particular data
patterns are changed prior to being written on the disk
surface as a pattern of On and Off or 1 and 0 signals.
EXTERNAL DRIVE – A drive mounted in an enclosure
separate from the PC or computer system enclosure, with its
own power supply and fan, and connected to the system by
a cable.
FAT – Acronym for file allocation table. A data table stored
on the outer edge of a disk that tells the operating system
which sectors are allocated to each file and in what order.
FCI – Acronym for flux changes per inch. See also BPI.
FILE SERVER – A computer that provides network
stations with controlled access to shareable resources. The
network operating system is loaded on the file server, and
most shareable devices (disk subsystems, printers) are
attached to it. The file server controls system security and
monitors station-to-station communications. A dedicated
file server can be used only as a file server while it is on the
network. A non dedicated file server can be used
simultaneously as a file server and a workstation.
FLUX DENSITY – The number of magnetic field
patterns that can be stored in a given length of disk surface.
The number is usually stated as flux changes per inch (FCI),
with typical values in the thousands.
FLYING HEIGHT – The distance between the
read/write head and the disk surface caused by a cushion of
air that keeps the head from contacting the media. Smaller
flying heights permit more dense storage of data, but require
more precise mechanical designs.
FORMAT – To write onto the disk surface a magnetic track
pattern that specifies the locations of the tracks and sectors.
This information must exist on a disk before it can store any
user data. Formatting erases any previously stored data.
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