Chapter 8 Details of Usage
Page 8 - 16 |
| Target Mode Usage and SCSI Protocol Handling |
Clear Queue - Treat this command as a series of Abort messages that are received from each initiator. This message is sent to the host while holding the SCSI bus. It is the responsibility of the host to instruct the adapter to go to the Bus Free phase after all necessary commands are aborted.
Identify - A single identify message must be sent to the adapter each time it is selected as a target device. The adapter will send a Message Reject message to the initiator if it sends an Identify message at any other time.
Initiator Detected Error - If this message occurs after a Data phase or a Status phase, the target retries the current activity. The Restore Pointers message will be sent first. This message is handled by the adapter up to the retry limit specified in the adapters configuration data. If this message occurs after any other phase, it is sent to the host using the Message Byte Received byte.
Message Parity Error - The last message byte sent to the initiator had a parity error. Return to the Message In phase and resend the entire message that had the detected parity error. If the target is not sending message bytes to the initiator and this message comes in, the target will go to the Bus Free phase (a catastrophic error). In this case, the message will be sent to the host so it may create the correct sense data. This message is handled by the adapter up to the retry limit specified in the adapter’s configuration data.
Message Reject - The last message byte sent was inappropriate or not implemented. If the target is not sending message bytes when this message is received, it will reject this message. This message is sent to the host while holding the SCSI bus. It is the responsibility of the host to instruct the adapter what to do next.
No Operation - The initiator does not currently have a valid message to send. Forget about it and continue. This can happen if the target does not respond to an attention condition until a later phase. The adapter will ignore this message and resume whatever action was in process when the ATN was received.
Head of Queue Tag (2 bytes) - Place this I/O process first in the LUN’s command queue. This message is sent to the host in the queue tag message field of the selection command. If less than the required 2 bytes are received, the adapter will send the initiator a message reject.
Ordered Queue Tag (2 bytes) - Place this I/O process into the LUN’s command queue to be executed in the order received. This message is sent to the host in the queue tag message field of the selection command. If less than the required two bytes are received, the adapter will send the initiator a message reject.
Simple Queue Tag (2 bytes) - Place this I/O process into the LUN’s command queue. This message is sent to the host in the queue tag message field of the selection command. If less than the required two bytes are received, the adapter will send the initiator a message reject.
21020285 D | User’s Guide |
