HGST Ultrastar 7K4000 (SAS) Hard Disk Drive Specification
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Table 99: Mode parameter header (10)
• Mode Data Length. When using the MODE SENSE command, the mode data length field specifies the length in bytes
of the following data that is available to be transferred. The mode data length does not include the length byte itself.
When using the MODE SELECT command, this field is reserved.
• Medium Type field is always set to zero in the drive (Default Medium Type).
• WP. When used with the MODE SELECT command, the Write Protect (WP) bit is reserved.
When used with the MODE SENSE command, a Write Protect (WP) bit of zero indicates that the medium is write
enabled.
• DPOFUA bit value of 1 indicates that the Target supports the FUA and DPO bits in the Read and Write Commands.
•LONGLBA bit value of 0 indicates that any following Block Descriptor uses the Short LBA Block Descriptor format. A
LONGLBA bit value of 1 indicates that any following Block Descriptor uses the Long LBA Block Descriptor format
• Block Descriptor Length specifies the length in bytes of the block descriptor. Values of 0, 8, and 16 are supported by the
Target, respectively corresponding to an absent Block Descriptor, a single Short LBA Block Descriptor, and a single
Long LBA Block Descriptor.
Note: DPOFUA is ignored during Mode Select command processing although the SCSI Standard states that it is reserved dur-
ing Mode Select. Ignoring it allows the Mode Sense Parameter List for the byte containing this bit to be re-used as a Mode
Select Parameter List.
Byte
Bit
765 4 3210
0 - 1 (MSB) Mode Data Length (LSB)
2 Medium Type = 0
3 WP=0 Reserved=0 DPOFUA =1 Reserved = 0
4 Reserved = 0 LongLBA
5 Reserved = 0
6 - 7 (MSB) Block Descriptor Length (LSB)
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