Fujitsu M2488, Руководство по эксплуатации продукта

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TAPE UNIT SCSI COMMANDS M2488 PRODUCT GUIDE
4-70 CG00000-011503 REV. A April 1997
4-3.16 READ BUFFER command 3Ch
The READ BUFFER command is used in conjunction with the WRITE BUFFER command as a
diagnostic function for testing target memory and the SCSI bus integrity. Other than synchronizing
any buffered write data to tape prior to performing the read buffer operation, the READ BUFFER
command does not alter the tape medium of the target.
4-3.16.1 READ BUFFER CDB Description
READ BUFFER is a ten-byte command. The bytes are shown below and described in Table 4-63.
Common fields are described in paragraph 4-3.1 on page 4-4.
BITS
BYTES 7 6 5 4 3 2 1 0
0 0 0 1 1 1 1 0 0
1 LUN Reserved Mode
2 Buffer ID
3 MSB
Buffer Offset 4
5 LSB
6 MSB
Allocation Length 7
8 LSB
9 Reserved Flag Link
Note: Changeable fields in the CDB are shaded.
Table 4-63. READ BUFFER Field Description
BYTE BIT VALUE DESCRIPTION
0 0-7 3Ch Operation code.
1 0-2 The Mode field is described in Table 4-64.
2 The Buffer ID field identifies a specific buffer within the target.
3-5
The Buffer offset specifies the offset in the buffer for the beginning of the data
transfer. The Buffer Offset contains a multiple of the offset boundary field which
is in the read buffer descriptor.
6-8
The Allocation Length specifies the maximum number of bytes that are trans-
ferred during the DATA IN phase from the assigned buffer beginning at the
buffer offset. The transfer length is the lesser of the Allocation Length or capac-
ity of the requested buffer. The capacity of the buffer is shown in Table 4-65.