Mode Select (15) - Hitachi HUS151473VL3800 - Ultrastar 73.4 GB Hard Drive Specifications

17.8 MODE SELECT (15)

Table 67: Mode Select (15)
Byte
7
0
1 Reserved = 0
2
3
4
5 VU = 0
The MODE SELECT (15) command provides a means for the Initiator to specify LUN or device parameters to the Target. It
also allows an Initiator to specify options the Target uses in error recovery, caching, and formatting.
There is a single set of Mode Page parameters shared by all Initiators.
• PF A PF (Page Format) bit value of one indicates that the data sent by the Initiator after the Mode Select Header and the
Block Descriptor, if any, complies to the Page Format. The Target ignores this field since it only accepts mode param-
eters in the Page Format.
• SP Save Pages. This indicates
0 The drive shall not save the pages sent during the Data Out phase but will use them for all following commands
until the power is removed, a reset is received, or a new MODE SELECT command is received.
1 The drive will save the data in the reserved area of the disk. It will be used for all the following commands until
another MODE SELECT command is issued. This information is maintained over a power cycle or reset of the
drive.
• Parameter List Length This specifies the number of bytes to be sent from the Initiator. A parameter list length of zero
suppresses data transfer and is not considered an error.
The MODE SELECT parameter list contains a 4-byte header followed by zero or one block descriptor followed by zero or
more pages. The pages that are valid with this command are defined in the addendum under the heading Mode Select Data, as
they vary with the drive model.
Application Note
The Initiator should issue a MODE SENSE command requesting all Changeable values (see PCF field in byte two of the CDB
in) prior to issuing a MODE SELECT command. This is necessary to find out which pages are implemented by the drive and
the length of those pages. In the Pages of the MODE SENSE command the drive will return the number of bytes supported for
each Page. The Page Length set by the Initiator in the MODE SELECT command must be the same value as returned by the
drive in MODE SENSE Page Length. If not, the drive will return Check Condition status with sense key of Illegal Request.
Note: If an Initiator sends a MODE SELECT command that changes any parameters that apply to other Initiators, the drive
shall generate an unit attention condition for all Initiators except for the one that issued the MODE SELECT command. The
drive shall set the additional sense code to Parameters Changed (2Ah).
6 5 4
Command Code = 15h
PF=1
Reserved = 0
Parameter List Length
Reserved = 0
Hitachi Ultrastar 15K147 SCSI Hard Disk Drive Specification
Bit
3 2
Reserved = 0
FLAG
103
1 0
SP
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