Fujitsu M2488 Mode Select command 15h, Mode Select CDB Description, Mode Select Field Description

M2488 PRODUCT GUIDE TAPE UNIT SCSI COMMANDS

4-3.12 MODE SELECT command 15h

The MODE SELECT command provides a means for the initiator to specify medium, logical unit, and peripheral device parameters to the target by sending data relevant to such parameters in a DATA OUT phase during the command. Initiators should issue MODE SENSE prior to MODE SELECT to determine supported pages, page lengths, and other parameters. A single set of MODE SELECT parameters kept by the controller is common to all initiators for a specific LUN. The MODE SELECT command can be completed without error whether or not the LUN is ready. Buff- ered write data is synchronized to tape prior to activating the new mode parameters.

4-3.12.1 MODE SELECT CDB Description

MODE SELECT is a six-byte command. The bytes are shown below and described in Table 4-42. 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		1				0	1	0		1
1
		LUN					PF			Reserved					SP
2								Reserved
3								Reserved
4
						Parameter List Length
5
				Reserved								Flag		Link

Note: Changeable fields in the CDB are shaded.

Table 4-42. MODE SELECT Field Description

BYTE	BIT	VALU	DESCRIPTION
		E
0	0-7	15h	Operation Code.
1	0	0	A Save Pages (SP) bit of zero indicates the target shall perform the specified MODE
			SELECT operation, and shall not save any pages in non-volatile memory.
		1	A SP bit of one indicates that the target shall perform the specified MODE SELECT
			operation, and shall save to a non-volatile location all the savable pages sent during
			the DATA OUT phase.
1	4	0 or 1	A PF (Page Format) bit of 0 or 1 both indicate that the MODE SELECT parameters
			are structured as pages of related parameters as defined by the ANSI standard.
4	0-7		The Parameter List Length field specifies the length in bytes of the MODE SELECT
			parameter list to be transferred from the initiator to the target. A parameter list length
			of zero indicates that no data is transferred. This condition is not considered an error.

The Unit Attention/Mode Parameters Changed sense data will be reported to other initiators after a Mode Select command if and only if the setting of at least one parameter was actually changed from its previous setting. Therefore, issuing a Mode Select command with parameters that are the

April 1997 CG00000-011503 REV. A 4-51