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EOD, but because it is after EOD, this old data is no longer valid.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