HP LTO Ultrium 4 drives technical reference manual, volume 2: software integration 91
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Glossary
ANSI American National Standards Institute, which sets standards for, amongst other things,
SCSI and the safety of electrical devices.
BOM Beginning Of Media. The first point on the tape that can be accessed by the drive.
buffered mode A mode of data transfer in write operations that facilitates tape streaming. It is selected
by setting the Buffered Mode Field to 1 or 2 in the SCSI
MODE SELECT Parameter List
header.
compression A procedure in which data is transformed by the removal of redundant information in
order to reduce the number of bits required to represent the data.
compression ratio A measure of how much compression has occurred, defined as the ratio of the amount
of uncompressed data to the amount of compressed data into which it is transformed.
The LTO-DC algorithm can typically achieve a compression ratio of between 2:1 and
4:1 depending on the nature of the data.
decompression A procedure in which the original data is generated from compressed data.
ECMA European Computer Manufacturers Association. The European equivalent of ANSI.
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because it is after EOD, this old data is no longer valid.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.
FRU Field Replaceable Unit, an assembly or group of components that is replaced in its
entirety by Service Engineers when it contains a fault.
hard error An uncorrectable data error.
host The host computer system acting as controller for the drive.
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.
