Reference Guide

Chapter 4 SCSI Commands
READ Command (08h)
DLT-S4 Interface Reference Guide 235
Filemark and End-of-Data
Handling
4
If the drive reads a Filemark, it returns a CHECK CONDITION status.
Within the Sense Data, the Filemark and Valid bits are set to 1 and the
Sense Key field is set to
NO SENSE. The information fields contain the
residue count. The Additional Sense Code and Additional Sense Code
Qualifier fields are set to
FILEMARK DETECTED. Upon termination, the
drive logically positions the medium after the Filemark.
If the drive detects End of Data (EOD) during a
READ, it returns CHECK
CONDITION
status. Within the Sense Data, the Valid bit is set to 1 and the
Sense Key field is set to
BLANK CHECK. The information fields contain the
residue count. The Additional Sense Code Qualifier fields are set. Upon
termination, the drive physically positions the medium after the last block
on tape.
End-of-Medium/Partition
Handling
4
The meaning of EOM is different for a READ command than it is for a
WRITE-related command. The drive reports EOM only when it encounters
the physical EOM or End-of-Partition (EOP). The drive returns a
CHECK
CONDITION
status. The EOM and Valid bits are set to 1 and the Sense Key
field is set to
MEDIUM ERROR. The information fields contain the residue
count and the Additional Sense Code and Additional Sense Code
Qualifier fields are set to
EOM / P DETECTED. The drive physically
positions the medium at
EOM / P.
Transfer
Length
When set to 1, specifies the number of blocks to be transferred to the initiator. This
setting is valid only if the drive is currently operating in fixed-block mode.
When set to 0, no data is transferred and the current position on the drive does not
change. This is not an error condition.
A successful
READ operation with the Fixed bit set to 1 transfers x byes of data, where
x = (current block length)
× (# of blocks) × (block size) bytes of data to the initiator.
Upon termination of the
READ command, the drive logically positions the medium
after the last block of data transferred (EOM side).
Field Description