Quantum DLT 8000 Product Manual page 365

WRITE Command (0Ah) (continued)
Table 5–101 WRITE Command Data — Field Descriptions
Field Name
Fixed
Transfer Length
Exception Conditions
If End of Tape (EOT) is detected while writing, the tape drive finishes writing any
buffered data. The command terminates with CHECK CONDITION status. Within the
sense data, the EOM bit is set, the Sense Key is set to NO SENSE, and the Additional
Sense code and Additional Sense Code Qualifier fields are set to EOM/P detected. The
drive attempts to complete any subsequent writes, returning a CHECK CONDITION
status in each case.
Description
The fixed bit specifies both the meaning of the Transfer Length field
and whether fixed-length or variable-length blocks are to be
transferred.
When the Fixed bit is 0, Variable-length block mode is selected. A
single block is transferred from the initiator and is written to the
logical unit beginning at the current logical tape position. Upon
successful termination, the tape is logically positioned after this block
(on the Enod of Media/Partition, or EOM/P side). The Transfer Length
specifies the number of bytes that the drive handshakes out from the
initiator as one block.
When the Fixed bit is 1, the Transfer Length field specifies the number
of blocks to be transferred to the host beginning at the current tape
position. This form of WRITE is valid only if the logical unit is currently
operating in the Fixed Block mode – when it has been instructed to
use fixed-length blocks with MODE SELECT. The current block length
is the block length defined in the MODE SELECT command. Upon
termination, the tape is logically positioned after these blocks.
This field contains the length of the data transfer in bytes or blocks
depending on whether Fixed or Variable block mode is selected.
When the Transfer Length is 0, no data is transferred and the current
position on the logical unit is not changed.
Quantum DLT 8000 Tape System
SCSI Commands
5-221