User's Manual

DLT2000 SCSI Interface
8-90 DLT2000/DLT2700 Cartridge Tape Subsystem
8.4.12 READ (08h)
Bit
76543210
0 Operation Code (08h)
Logical Unit Number Reserved SILI Fixed
(MSB)
Byte Transfer Length
Unused Reserved
1
Flag
(LSB)
2
Link
3
4
5
Figure 8-57 READ CDB
READ transfers one or more data blocks to the initiator starting with the next block on
the drive.
Fixed
This bit specifies the meaning of the Transfer Length field and whether fixed-length or
variable-length blocks are to be transferred.
If the Fixed bit is set to zero, a Variable Block mode is requested. A single block is
transferred with the Transfer Length specifying the maximum number of bytes the
initiator has allocated for the returned data.
If the Fixed bit is set to one, the Transfer Length specifies the number of blocks to be
transferred to the initiator. This is valid only if the logical unit is currently operating in
Fixed Block mode.
When the Transfer Length is zero, no data is transferred and the current position on the
logical unit is not changed.
A successful READ with the Fixed bit set to one transfers (current block
length)×(Transfer Length) bytes of data to the host. Upon termination of READ, the
media is logically positioned after the last block transferred (EOM side).
Suppress Incorrect Length Indicator (SILI)
If the SILI bit is one and the fixed bit is one, the target shall terminate the command
with CHECK CONDITION status and the sense key shall be set to ILLEGAL
REQUEST with an additional sense code of INVALID FIELD in CDB.
If the SILI bit is not set and the actual block length is different from the specified
transfer length, a CHECK CONDITION status is returned. Within the Sense data, the