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

Sequential access devices store data sequentially in the order in which it is

 

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 SCSI

spacing

Spacing is moving along the tape over a specified number of blocks or filemarks,

 

or to EOD, in order to find data quickly.

sub-data set

One sixteenth of a data set

synchronous

see data transfer phase

TapeAlert

A set of 64 flags is held in the TapeAlert log that indicate faults or predicted faults

 

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.

vendor-unique

The addition of commands to SCSI that are not included in the standard.

190 Glossary