Reference Guide

Chapter 4 SCSI Commands
READ Command (08h)
DLT-S4 Interface Reference Guide 234
Table 129 READ Command
Descriptor Block
— Field
Descriptions
5 Control
Field Description
SILI Suppress Incorrect Length Indicator. If the SILI bit is set to 1 and the Fixed bit is set to
1, the drive terminates the command with
CHECK CONDITION status, Sense Key set to
ILLEGAL REQUEST, and Additional Sense Code set to INVALID FIELD IN CDB.
If the SILI bit is set to 0 and the actual block length is different than the specified
transfer length, the drive returns
CHECK CONDITION status. Within the Sense Data, the
Incorrect Length Indicator (ILI) bit and Valid bit are set to 1. The Sense Key field is set
to
NO SENSE. The information bytes are set to the difference (residue) between the
requested transfer length and the actual block length, or, in Fixed Block mode, the
difference (residue) between the requested number of blocks and the actual number of
blocks read. No more than Transfer Length blocks are transferred to the initiator and
the drive logically positions the tape after the block (EOM side).
If the SILI bit is set to 1:
•The drive reports
CHECK CONDITION status for an incorrect length condition only if
the overlength condition exists and the Block Length field in the mode parameter
block descriptor is non-zero, or
• The drive does not report
CHECK CONDITION status if the only error is the
underlength condition or if the only error is the overlength condition and the Block
Length field of the mode parameters block descriptor is set to 0.
Fixed Specifies whether the drive is to transfer fixed-length or variable-length blocks and
gives meaning to the Transfer Length field of the
READ command.
When set to 0, requests variable-block mode. A single block is transferred with the
Transfer Length specifying the maximum number of bytes the initiator has allocated
for the returned data. When set to 1, requests fixed-block mode.
Bit
7 6 5 4 3 2 1 0
Byte