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Glossary
This glossary defines the special terms,
abbreviations, and acronyms that are used in this
publication.
Numbers
2:1 compression. The relationship between the
quantity of data that can be stored with compression as
compared to the quantity of data that can be stored
without compression. In 2:1 compression, twice as
much data can be stored with compression as can be
stored without compression.
A
A. See ampere.
active. The condition that the SCSI bus is in when a
server is trying to use one or more devices on the bus.
adapter. See adapter card.
adapter card. A circuit board that adds function to a
computer.
AL_PA. See Arbitrated Loop Physical Address.
amp. See ampere.
ampere (A, amp). A unit of measure for electric
current that is equivalent to a flow of one coulomb per
second, or equivalent to the current produced by one
volt applied across a resistance of one ohm.
Arbitrated Loop Physical Address (AL_PA). An 8-bit
value that identifies a device in an arbitrated loop. All
Fibre Channel ports communicate by using AL_PAs.
autosense data. Sent by the drive to the server,
sense data that automatically accompanies a Check
Condition in response to an error. The server does not
need to send a REQUEST SENSE command to get the
sense data. Autosense data is available only in the
Fibre Channel version of the Ultrium Tape Drive (Model
T200F).
B
backups. The short-term retention of records used for
restoring essential business and server files when vital
data has been lost because of program or server errors
or malfunctions.
backreflection. Pertaining to instances where light is
launched into an optical fiber in a forward direction, the
light that is returned to the launch point in the reverse
direction.
bar code. A code that represents characters by sets of
parallel bars of varying thickness and separation. The
bars are read optically by transverse scanning.
bar code label. A slip of paper bearing a bar code and
having an adhesive backing. The bar code label must
be affixed to a tape cartridge to enable the library to
identify the cartridge and its volume serial number.
bezel. The removable frame that fits over the front of
the Ultrium Tape Drive.
burst data transfer rate. The maximum speed at
which data is transferred.
bus. See SCSI bus.
byte. A string that consists of a certain number of bits
(usually 8) which are treated as a unit and represent a
character. A byte is a fundamental unit of data.
C
C. See Celsius.
capacity. The amount of data that can be contained
on storage media and expressed in bytes.
cartridge. See tape cartridge.
cartridge door. On a tape cartridge, the hinged barrier
that can be opened to access, or closed to protect, the
magnetic tape within the cartridge.
cartridge manual rewind tool. A device that can be
fitted into the reel of a cartridge and used to rewind tape
into or out of the cartridge.
cartridge memory. See LTO cartridge memory.
Celsius. Having a thermometric scale on which the
interval between the freezing point and the boiling point
of water is divided into 100 degrees, with 0°
representing the freezing point and 100° representing
the boiling point.
circuit board. A thin sheet on which chips and other
electronic components are placed. Computers consist of
one or more boards, often called cards or adapters.
cleaning cartridge. A tape cartridge that is used to
clean the heads of a tape drive. Contrast with data
cartridge.
clockwise. In the direction that the hands of a clock
rotate, as viewed from the front.
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