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5.SCSI Interface
5.4. Status Specification
A Status byte is sent from the drive to the Host during the STATUS phase at the termination of each command as
specified in the SCSI specification, unless the command has been cleared by an ABORT message, by a BUS
DEVICE RESET message, or by a hard RESET.
The Status bytes that will be return are:
00h
GOOD: This status indicates that the drive has successfully completed the command.
02h
CHECK CONDITION: Any error, exception, or abnormal condition that causes sense data to be set returns
CHECK CONDITION. The REQUEST SENSE command should be sent following this status to determine
the nature of the error.
08h
BUSY: The drive is busy. This status is returned whenever the drive is unable to accept a command from
an otherwise acceptable initiator. The BUSY status will be returned by the unit, if, while it is
DISCONNECTED from the SCSI bus, it receives a command from a different initiator. The unit does not
stack commands and therefore will not accept the next command until the current one has completed.
Note that if an initiator sends overlapped commands to the unit (i.e.: it sends a new command while the
previous one is still executing and the unit is disconnected) then the first command will be aborted and a
CHECK CONDITION will be returned to the initiator to indicate that the command was aborted. The
second command will NOT be executed.
The BUSY status returned by the drive must not be confused with DRIVE NOT READY. DRIVE NOT
READY will be returned as part of the Sense data following a REQUEST SENSE command and indicates
that the drive is off-line and no media is loaded in the drive.
The drive is deemed off-line if the tape is currently unloaded and, normally, ejected from the drive.
However, the drive will still be off-line if the tape has been retained within the drive following a Host issued
PREVENT MEDIA REMOVAL command prior to the unload.
In the off-line state, the Host cannot perform any operation which would cause tape motion. These
commands will return a CHECK CONDITION status with a DRIVE NOT READY sense key set. The
command types which are not allowed are write, read, verify or space commands. The Host may load the
tape when the unit is off-line so long as the tape has been prevented from being ejected via the
PREVENT/ALLOW MEDIA REMOVAL command.
While the drive is "Busy" the Host may issue any command, including diagnostic commands, which do not
access the tape and a GOOD status shall be returned.
INQUIRY
LOG SELECT
LOG SENSE
MODE SELECT
MODE SENSE
PREVENT ALLOW MEDIUM REMOVAL
READ BLOCK LIMITS
READ BUFFER
RECEIVE DIAGNOSTIC RESULTS
RELEASE UNIT
REQUEST SENSE
RESERVE UNIT
SEND DIAGNOSTIC
WRITE BUFFER
The TEST UNIT READY command is used to determine the on-line/off-line state of the drive and will,
therefore, return a CHECK CONDITION status with a DRIVE NOT READY sense key set if no media is
currently loaded.
5-12
These commands are:
SONY AIT-3Ex drive SDX-800V series Ver.1.0
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