Operating instructions

SEPTEMBER 2005 PRELIMINARY MAGNUM 1X7 LTO AUTOLOADER
2-5
COMMUNICATION ACROSS THE SCSI BUS
Table 2-2 SCSI messages supported by the autoloader
Message
Hex
Value
Description
Task
Complete
00h The autoloader informs the initiator that the execution of the command was
completed and that it sent a valid status byte to the initiator.
Extended
Messages
01h Synchronous Data Transfer Request (01h) The autoloader supports synchronous
data transfer.
Wide Data Transfer Request (03h) The autoloader supports wide data transfer.
Save Data
Pointers
02h The autoloader requests that the initiator copy the current data pointer for possible
use by the Restore Pointers message during error recovery.
Restore
Pointers
03h The autoloader informs the initiator that it did not properly receive a block of data
or the command descriptor block (CDB) and that the data needs to be transferred
again.
Disconnect 04h The autoloader informs the initiator that it plans to disconnect from the SCSI bus and
that a reconnect will be required later.
Initiator
Detected
Error
05h The initiator informs the autoloader that an error occurred. The autoloader can retry
the operation.
Abort Task
Set
06h The initiator is clearing the present and any pending operation for that initiator.
When the autoloader accepts this message, it releases the bus into the Bus Free
phase.
Message
Reject
07h Either the initiator or the autoloader is indicating that the last message received was
inappropriate or not implemented.
No
Operation
08h The initiator informs the autoloader that it does not have a valid message to send in
response to the autoloader’s request for a message.
Message
Parity Error
09h The initiator informs the autoloader that one or more bytes in the last message it
received had a parity error.
Tar ge t
Reset
0Ch The initiator instructs the autoloader to reset all of its current I/O operations for all
initiators. The autoloader releases the SCSI bus into the Bus Free phase, with no
operations pending for any initiator, and performs a reset. (See page 3-2 for more
information about resetting the autoloader.)
Ignore
Wide
Residue
23h The autoloader sends the Ignore Wide Residue message to indicate that the number
of valid bytes sent was less than the negotiated transfer width.
Identify 80h
or
C0h
This message is used to establish a physical path connection between the initiator
and the autoloader. It also indicates whether disconnect is supported and the LUN
for which the command is intended. The autoloader supports a LUN of 0.