Quantum LTO 4, User Manual

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SCSI Commands: 30BREAD BLOCK LIMITS Page 139
3.18 READ BLOCK LIMITS
The READ BLOCK LIMITS command requests that the drive return the maximum
and minimum block sizes that it supports. The minimum block length is always
reported as 1 byte, the maximum as 2
24
-1 bytes.
3.18.1 READ BLOCK LIMITS Command Descriptor Block
Byte
Bits
7 6 5 4 3 2 1 0
0 Operation Code (05h)
1 Ignored LUN Reserved
2 Reserved
3 Reserved
4 Reserved
5 Control
3.18.1.1 READ BLOCK LIMITS Command Field Descriptions
Field Bytes Bits Description
Operation
Code 0 The Operation Code for READ BLOCK LIMITS is 05h
Ignored
Logical Unit 1 5-7 The LUN field is vestigial from the SCSI-1 standard and is ignored.
Reserved All reserved bits must be 0.
Control 5 See SCSI Command Control Byte Format on page 25.
The host specifies the actual block size in fixed mode with the MODE SELECT
command and in variable mode with the transfer/allocation length of Read and Write
commands. The use of the MODE SENSE command determines the current block
size. The READ BLOCK LIMITS command indicates the minimum and maximum
block size that the drive can support.
3.18.2 READ BLOCK LIMITS Data
The READ BLOCK LIMITS command returns data in the following format.
Byte
Bits
7 6 5 4 3 2 1 0
0 Reserved
1 (MSB)
2
3
Maximum Block Length
(LSB)
4 (MSB)
5
Minimum Block Length
(LSB)