Technical data

Device Support on OpenVMS Systems

7.20 Stricter Requirement for Mode Page 01h on SCSI Tape Drives

V7.3

OpenVMS Alpha Version 7.3 has implemented stricter requirements for SCSI

Mode Page 01h (the Read Write Error Recovery Page) for SCSI tape drives.

These requirements help guard against possible data loss during write operations

to SCSI tape, by deﬁning the recovery actions to be taken in the event of deferred

recoverable errors. For most Compaq-supported drives, these changes will not

affect the drive’s behavior. For some drives, however, these new requirements

may impact SCSI tape behavior in the following two ways:

1. OpenVMS Alpha V7.3 now creates an error log entry whenever the ﬁrmware

of a SCSI tape drive is found not to support the Read Write Error Recovery

Page (SCSI mode page 01h). Such an entry is made in the error log at the

time the tape is mounted. The entry is characterized by a SCSI Status of

Check Condition, with a Sense Key of Illegal Request, on a Command Opcode

of Mode Sense.

This entry is informational only, and not indicative of an error condition

on the drive. It may be ignored by the user, and is of use only to service

personnel. It may occur on a number of different SCSI tape drives, including

the TLZ09, as well as on various third party tape drives.

2. If a deferred recoverable error occurs on a SCSI tape drive, then OpenVMS

Alpha V7.3 recognizes that data may have been lost, and therefore a fatal

drive error is returned to the caller. This behavior is unlikely to occur on

Compaq-supported SCSI tape drives, because their default behavior is to

suppress deferred recoverable errors.

Device Support on OpenVMS Systems 7–13