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Ultra SCSI supports both SE and LVD interfaces. In normal situations, slower
devices can coexist with faster devices, and narrow devices can be used on the
same SCSI bus as wide devices using a suitable adapter.
HP's Generation 1 Ultrium drives are Ultra2, wide SCSI-3 compatible devices.
They can be used with both LVD and SE host bus adapters.
Generation 2 Ultrium drives are Ultra160, wide SCSI-3 compatible.
Generation 3 Ultrium drives are Ultra320 compatible; however for performance
reasons they should not be used on an SE bus.
sense data
Data returned after the execution of a SCSI command, telling the host whether the
transaction was successful, and if not, what went wrong.
Sequential access devices store data sequentially in the order in which it is
sequential access
received. Tape devices are the most common sequential access devices. Devices
such as disk drives are direct access devices, where data is stored in blocks, not
necessarily sequentially. Direct access allows for speed of retrieval, but is
significantly more costly.
single-ended
see
spacing
Spacing is moving along the tape over a specified number of blocks or filemarks,
or to EOD, in order to find data quickly.
One sixteenth of a
sub-data set
see
synchronous
A set of 64 flags is held in the TapeAlert log that indicate faults or predicted faults
TapeAlert
with the drive or the media. By reading this log, host software can inform the user
of existing or impending conditions, and can, for example, advise the user to
change the tape.
The addition of commands to SCSI that are not included in the standard.
vendor-unique
190
Glossary
SCSI
data set
data transfer phase
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