IBM Ultrium Internal Tape Drive T200, Справочное руководство

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READ
Table 48. READ Command
7 6 5 4 3 2 1 0
0 Operation Code (08h)
1 Logical Unit Number (0) Reserved SILI Fixed
2
:
4
Transfer Length
5 Control
The READ command causes data to be transferred from the tape medium to the
initiator.
If the Fixed flag is clear and Transfer Length is not 0, then a single block of the
length in Transfer Length is to be transferred. If the next block on tape is of this
length or shorter, then it is transferred to the initiator. If the next block is longer than
this length, then only the length requested is returned and the logical position is set
to after the record. If the length of the block was the same as the Transfer Length
field, then Good status is returned. For additional details about Suppress Illegal
Length Indicator (SILI) management, see SCSI-3 Stream Commands (SSC),
available on the Web at
http://www.t10.org
.
If the Fixed flag is set, the Transfer Length field is not 0, and the Suppress Illegal
Length Indicator (SILI) flag is clear, then a sequence of blocks of the currently
configured block length is to be returned, the number of blocks being indicated in
the Transfer Length field. If there is a sequence of blocks of this length on the tape,
they are returned to the initiator with Good status. If a block that is longer than the
configured length is encountered before the sequence is complete, the blocks up to
that block are returned, followed by the configured length from the record that was
too long and Check Condition status. If a block that is shorter than the configured
length is encountered before the sequence is complete, the blocks up to that block
are returned, followed by all of that block and Check Condition status. The current
position is set after the last block that was returned or partially returned.
If the Transfer Length field is 0, and if the Suppress Illegal Length Indicator and the
Fixed bit are not both set, then no action is taken.
If Suppress Illegal Length Indicator (SILI) flag is set and the Fixed bit is set, then
Check Condition status is returned. The Sense Key is set to Illegal Request and the
ASC/ASCQ is set to Invalid Field in CDB (2400).
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Ultrium Internal Tape Drive and 3580 Ultrium Tape Drive: SCSI Reference