•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

UNIT 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).

Commands

REQUEST SENSE 03h 155