Quantum LTO 4, Руководство пользователя

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SCSI Commands: 32BREAD POSITION Page 145
3.20 READ POSITION
The READ POSITION command reports the block address of the current data block.
The current data block is the first data block that would be read from the current tape
partition if a READ command were issued.
3.20.1 READ POSITION Command Descriptor Block
Byte Bits
7 6 5 4 3 2 1 0
0 Operation Code (34h)
1 Ignored LUN Reserved TCLP Long Rsvd
2 Reserved
3 Reserved
4 Reserved
5 Reserved
6 Reserved
7 Reserved
8 Reserved
9 Control
3.20.1.1 READ POSITION Command Field Descriptions
Field Bytes Bits Description
Operation
Code 0 The Operation Code for READ POSITION is 34h.
Ignored
Logical
Unit
1 5-7 The LUN field is vestigial from the SCSI-1 standard and is ignored.
TCLP 1 2 1 = The drive returns data specifying the partition, file and set
number with the current logical position.
0 = The drive returns data specifying the first and last block
location.
The Long bit and the TCLP bit must be equal, otherwise, the
command shall be terminated with Check Condition status. The
sense key shall be set to Illegal Request, and the additional sense
code and an additional sense code qualifier set to Invalid Field in
CDB.
Long 1 1 1 = The drive shall return 32 bytes of data.
0 = The drive shall return 20 bytes of data.
The Long bit and the TCLP bit must be equal, otherwise, the
command shall be terminated with Check Condition status. The
sense key shall be set to Illegal Request, and the additional sense
code and an additional sense code qualifier set to Invalid Field in
CDB.
Reserved 2-8 All reserved bits must be 0.
Control 9 See SCSI Command Control Byte Format on page 25.