Chapter 3 Error Recovery; Error Conditions And Retry Procedure - Fujitsu MBA3073 SERIES Technical Manual

CHAPTER 3
This chapter describes the SCSI bus errors and their recovery by the HDD.
Note:
If a severe error has occurred, the HDD may switch the SCSI bus to the BUS FREE phase
without sending the DISCONNECT or TASK COMPLETE message to the INIT. In such
case, the HDD clears all information of the currently executing commands and does not report
the command completion (or reconnection) to the INIT.
If the SCSI bus is switched to the BUS FREE phase in a sequence other than the normal bus
sequence, the INIT shall consider that the currently executing command has terminated
abnormally. In such case, the HDD may or may not generate a sense data of this error.
However, the INIT should issue the REQUEST SENSE command to obtain the error
information.
3.1

Error Conditions and Retry Procedure

(1) MESSAGE OUT phase parity error
When the HDD detects a parity error of the SCSI bus during the MESSAGE OUT phase, it retries
the MESSAGE OUT phase up to 3 times. If the HDD fails to recover a parity error, it proceeds to
the next procedure. For details, see Section 1.6.9.
If the LUN is already identified, the HDD terminates the currently executing command with the
CHECK CONDITION status. At this time, the sense key/sense code of the sense data indicates
the "ABORTED COMMAND [=B]/SCSI parity error [=47-00]." If this happens after the status is
reported, the HDD enters the BUS FREE phase and the same sense data is retained. The HDD
ignores the ATTENTION condition until it enters the BUS FREE phase. If the LUN is not
identified by the IDENTIFY message or the LUN field of CDB, the HDD does not generate the
sense data and enters the BUS FREE phase immediately.
C141-C015
ERROR RECOVERY
3.1 Error Conditions and Retry Procedure
3.2 Recovery Control
187