
SCSI Commands
Quantum DLT 4000 Tape Drive 5-7
5.1.3 Status/Error Reporting
SCSI message-level errors are communicated by messages that are defined
specifically for that purpose (for example, MESSAGE PARITY ERROR,
MESSAGE REJECT). Message-level errors are also handled by drive-managed
retries. Refer to Chapter 4 for more detailed message-handling information.
SCSI command-level errors are communicated by a status code that is returned
by the drive during the STATUS phase. This phase occurs at the end of each
command, unless the command is terminated by one of the following events:
• ABORT message
• BUS DEVICE RESET message
• Hard reset condition
• Unexpected disconnect
The status code is contained in bits 1 through 5 of the status byte. Bits 0, 6, and
7 are reserved. Table 5–4 describes the status codes returned by the drive.
NOTE
In contrast to the BUSY status condition, the DRIVE NOT READY
Sense Key is returned as part of the Sense data following a REQUEST
SENSE command and indicates that a media access command has
been issued and the medium is not ready to be accessed. For
example, the medium is not installed, the medium has been
unloaded, and the drive is currently initializing the medium to
prepare it for access).
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