Sony SDX-800V/R manual Status Specification

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.	These commands are:
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 SONY AIT-3Ex drive SDX-800V series Ver.1.1