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HP C737990900 User Manual

Page 166

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166 glossary

(16-bit) data transfer, two bytes are transferred at the same time instead of a

single byte. HP Ultrium drives support asynchronous, synchronous and wide

transfers.

decompression

A procedure in which the original data is generated from compressed data.

DSIT

Data Set Information Table. Part of the

data set

that describes its contents.

ECMA

European Computer Manufacturers Association. The European equivalent of

ANSI.

enhanced commands

SCSI commands that are vendor-unique and not part of the common SCSI set.

EOD

End Of Data. An area that signifies the end of the valid data. If new data is

written over a larger quantity of old data, it is possible for data to exist after

EOD, but because it is after EOD, this old data is no longer valid.

EOM

End Of Media format. The last usable point on the tape.

EW-EOM

Early Warning End Of Media. A physical mark or a device-computed position

on the tape that tells the drive that it is approaching EOM.

filemark

A mark written by the host. It does not necessarily separate files; it is up to the

host to assign a meaning to the mark.

filemark count

The number of filemarks written since the beginning of the current tape up to

and including the current group.

FRU

Field Replaceable Unit, an assembly or group of components that is replaced

in its entirety by Service Engineers when it contains a fault.

host

The host computer system acting as controller for the drive.

immediate mode

A mode of responding to SCSI commands where the drive or other peripheral

does not wait until the command has finished before returning status

information back to the host. For writing filemarks, Immediate mode can

significantly improve the performance of systems that do not set the Immediate

bit when sending a SCSI Write Filemarks command. On the other hand, data

is not flushed to tape in response to a filemark command.

load

The process in which the drive takes in an inserted cartridge and goes online.

LUN

Logical Unit Number, by which different devices at a particular SCSI ID can be

addressed individually. The drive has a fixed LUN of 0.

LVD

Low-Voltage Differential. See

SCSI

.