REQUEST SENSE 03h
Commands
155
• It is cleared in response to the arrival of any command other than REQUEST SENSE or
INQUIRY.
• It is cleared following execution of a
REQUEST SENSE command.
• If the current command fails, sense is set according to the failure and
CHECK CONDITION is
reported to the host that sent the command.
• If the previous command terminated with an unexpected
BUS FREE, current sense is set
according to the reason for the bus release.
• If the command fails its pre-execution check for Unit Attention,
UNIT ATTENTION sense is
copied to the Current sense, and
CHECK CONDITION is reported to the host that sent the
command.
• If the command fails its pre-execution check for Deferred Error,
DEFERRED ERROR sense is
copied to the Current sense, and
CHECK CONDITION is reported to the host that sent the
command.
Clearing current sense:
Clearing the Current sense involves setting sense fields as follows:
Valid = 0
error code = 0x70
segment number = 0
ILI = 0
sense key = 0
information bytes = 0
command specific information = 0
fru code = 0
SKSV = 0
UNIT ATTENTION sense
UNIT ATTENTION sense is set when one of the following Unit Attention conditions occur:
• Power On, SCSI Reset, Bus Device Reset
• Media inserted
• A load command executed by a third party
• Mode Sense parameters changed by another initiator
• Drive firmware has been updated
U
NIT ATTENTION sense will persist for a host until the host sends a command that has Unit
Attention as part of its pre-execution checks. When the Unit Attention pre-execution check fails, the
UNIT ATTENTION sense is copied to the Current sense and CHECK CONDITION status is reported to
the host. The
UNIT ATTENTION sense is cleared. The host is then expected to issue a REQUEST
SENSE
command to recover the UNIT ATTENTION sense (which is now the new Current sense).
