User's Guide

Chapter 3 Emulated DLT7000 SCSI Commands
Write (0Ah)
272 Quantum DX-Series Software Interface Guide
Table 221 WRITE
Command Data - Field
Descriptions
Exception
Conditions
3
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.
Field Name Description
Fixed 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 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.
Transfer
Length
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.