Fujitsu M2488 manual Request Sense command 03h, Request Sense CDB Description

M2488 PRODUCT GUIDE TAPE UNIT SCSI COMMANDS

4-3.23 REQUEST SENSE command 03h

The REQUEST SENSE command requests that the target transfer sense data to the initiator. The con- troller is capable of supplying 44 bytes (2Ch bytes) of sense. Refer to section 8-3 on page 8-4 for a description of the sense data received via this command.

4-3.23.1 REQUEST SENSE CDB Description

REQUEST SENSE is a six-byte command as shown below and described in Table 4-99. Common fields are described in paragraph 4-3.1 on page 4-4.

						BITS
BYTES	7	6	5		4		3	2	1		0
0	0	0	0		0		0	0	1		1
1
		LUN						Reserved
2						Reserved
3						Reserved
4					Allocation Length
5
				Reserved						Flag		Link

Note: Changeable fields in the CDB are shaded.

Table 4-99. REQUEST SENSE Field Description

BYTE	BIT	VALUE	DESCRIPTION
0	0-7	03h	Operation code.
4	0-7		The Allocation Length field specifies the maximum number of sense data bytes
			to be returned to the initiator. An allocation length of zero indicates that no sense
			data is returned and is not considered an error. The target terminates the sense
			data transfer when the allocation length bytes have been transferred or when all
			of the sense data have been transferred to the initiator, whichever is less.
			The additional sense length in the sense data is not altered to reflect truncation
			due to insufficient allocation length.

4-3.23.2 REQUEST SENSE CHECK CONDITION Status

The sense data is valid for a CHECK CONDITION status returned on the prior command. This sense data is preserved by the target for the initiator until retrieved by the REQUEST SENSE com- mand or until the receipt of any other command for the same logical unit from the initiator that issued the command resulting in the CHECK CONDITION status. Sense data is cleared upon receipt of any subsequent command (including Request Sense) to the logical unit from the initiator receiving the CHECK CONDITION status.

The REQUEST SENSE command returns the CHECK CONDITION status only to report fatal errors for the REQUEST SENSE command.

April 1997 CG00000-011503 REV. A 4-103