Quantum 10K II - Manual (Page 239)

SCSI Description
5–172 Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives
REQUEST SENSE Command (03h) (continued)
5.34.2 Clearing Sense Data
Sense data is cleared from the drive's memory by one of the following conditions:
• After being returned from a REQUEST SENSE command.
• As soon as any other command is received from the initiator except INQUIRY.
5.34.3 Status Reporting
The drive returns CHECK CONDITION status for a REQUEST SENSE command
only to report errors specific to the command when:
•
A non-zero reserved bit is detected in the Command Descriptor Block.
• A drive malfunction prevents return of the sense data.
For Parallel SCSI disk drives, the drive also returns CHECK CONDITION status for
a REQUEST SENSE command to report errors specific to the command when an
unrecovered parity error is detected on the data bus.
Note that any of the previous conditions overwrites the current sense data with the
sense data describing the error encountered by the REQUEST SENSE command
(that is, for the condition stated in the first bulleted entry, the new sense data
reflects that a non-zero reserved bit was detected in the Command Descriptor Block).
The drive returns a maximum of 18 bytes of sense data. The initiator should set the
Allocation Length field in the Command Descriptor Block to 18 to receive all sense
data. If the Allocation Length is set to 0, four bytes of data will be returned (this
option maintains compatibility with SCSI-1 systems).
5.34.4 Sense Data Format for Error Code 70h and Error Code 71h
The sense data format for error code 70h (current error) and error code 71h (deferred
error) is shown in Figure 5-85; the data fields are defined in Table 5-83.