Mode Sense Page Descriptor Header - Seagate SCSI Interface Product Manual

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[7] The Block Length, as defined after a format function, specifies the length in bytes of each logical block
described by the Block Descriptor. Default is 512 if no Mode Select command is received before the For-
mat command. The usual valid values are 256 through 4096. Some drive products can format down to
180 bytes per sector. Some products can only format an even numbered value of bytes per sector (180 -
4096).
[8] When used with the Mode Sense command, a DPO-FUA bit of zero indicates that the target does not con-
tain a cache memory or does not support the DPO and FUA bits. A DPO-FUA bit of one indicates that the
target supports the DPO and FUA bits.
5.12.1

Mode Sense page descriptor header

Each page of mode parameters (for the Mode Sense command) begins with a two byte page descriptor
header. The Page Code identifies the page of mode parameters that is being transferred. The Page Length
indicates the number of additional bytes of mode parameters being sent by the drive. The parameter bit values
are left blank herein, because they may be different for each drive model.
Note. See individual drive's Product Manual, Volume 1, for a table giving the Mode Sense parameter values
that are applicable to the drive model of interest. The tables in Volume 1 also show which parameters
are changeable in the drive model of interest and which are not.
Multiple pages of mode parameters may be transferred in one Mode Sense Data In phase (using Page Code
3Fh). If a non-supported page code is requested by the Initiator, the drive terminates the command with Check
Condition status, sets the sense key to 05, Illegal Request, and sets the additional sense code to 24, Invalid
Field In Parameter List.
The Parameters Savable (PS) bit, when set to one, indicates if the page contains savable parameters. When
the PS bit is set to zero, none of the parameters within the page are savable. Since the parameters within
pages 3 and 4 are always saved during format commands (but not via a Mode Select command with the SMP
bit set to 1), these pages return a one for the PS bit.
Table 89: Mode Sense page descriptor header
Bit 7
Byte
0 PS
1 Page Length [1]
2–n Mode Parameters [1]
Notes.
Page Code Page Description
[1]
01h Error Recovery
02h Disconnect/Reconnect Control
03h Format Parameters
04h Rigid Drive Geometry
07h Verify Error Recovery
08h Caching Parameters
0Ah Control Mode
0Ch Notch
0Dh or 1Ah Power Condition
10h Xor Control Mode
00 h Unit Attention Parameters
1Ch Informational Exceptions Control
6 5
0
SCSI Interface Product Manual, Rev. J
4 3
Page Code [1]
Reference Table
90
91
92
93
94
95
96/97
98
99
100
101
102
2 1
Page
123
126
128
130
132
134
137/138
139
141
142
144
146
0