| 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 |
| They can be used with both LVD and SE host bus adapters. |
| Generation 2 Ultrium drives are Ultra160, wide |
| 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. |
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. |
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. |
The addition of commands to SCSI that are not included in the standard. |
190 Glossary