User Manual

SCSI Commands Reference Manual, Rev. J 379
www.seagate.com Parameters for direct access devices
MODE DATA LENGTH field
When using the MODE SENSE command, the MODE DATA LENGTH field indicates the length in bytes of the following data that is available to be
transferred. The mode data length does not include the number of bytes in the MODE DATA LENGTH field. When using the MODE SELECT com
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mand, this field is reserved.
MEDIUM TYPE field
The contents of the MEDIUM TYPE field are unique for each device type. Refer to the mode parameters subclause of the specific device type
command standard for definition of these values. Some device types reserve this field.
WP (Write Protect) bit
1 A WP bit set to one indicates that the medium is write-protected. The medium may be write protected when the software write protect
(SWP) bit in the Control mode page (see 5.3.12) is set to one or if another vendor specific mechanism causes the medium to be write pro-
tected.
0 A WP bit set to zero indicates that the medium is not write-protected.
DPOFUA (DPO and FUA support) bit
0 A DPOFUA bit set to zero indicates that the device server does not support the DPO and FUA bits.
1 When used with the MODE SENSE command, a DPOFUA bit set to one indicates that the device server supports the DPO and FUA bits
(see 3.16)
LONGLBA (Long LBA) bit
0 If the Long LBA (LONGLBA) bit is set to zero, the mode parameter block descriptor(s), if any, are each eight bytes long.
1 If the LONGLBA bit is set to one, the mode parameter block descriptor(s), if any, are each sixteen bytes long.
BLOCK DESCRIPTOR LENGTH field
The BLOCK DESCRIPTOR LENGTH field contains the length in bytes of all the block descriptors. It is equal to the number of block descriptors
times eight if the LONGLBA bit is set to zero or times sixteen if the LONGLBA bit is set to one, and does not include mode pages or vendor spe
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cific parameters (e.g., page code set to zero), if any, that may follow the last block descriptor. A block descriptor length of zero indicates that no
block descriptors are included in the mode parameter list. This condition shall not be considered an error.