Recovery Control - Fujitsu MBA3073 SERIES Technical Manual

3.2

Recovery Control

The HDD performs the error recovery for some kinds of SCSI bus errors (see Section 3.1). All
recovery procedures are based on the protocol of SCSI bus phase.
Note:
If the INIT does not generate an ATTENTION condition, the HDD does not use any message
except for the TASK COMPLETE message. Also, the HDD does not execute the MESSAGE
OUT phase. If a parity error is detected in the COMMAND phase, the HDD considers that the
LUN is not identified and it enters the BUS FREE phase immediately.
Table 3.1 gives and outline of the retry procedure for handling SCSI bus errors. If the HDD
performs the error recovery, Table 3.1 means the operation after the error recovery fails. The
symbols used in this table are as follows.
LUN I
N
X
GOOD
CHECK
→BUS FREE : The HDD enters a BUS FREE phase without sending a DISCONNECT or
–
192
: An LUN is already identified.
: An LUN is not yet.
: Don't care
: GOOD status
: CHECK CONDITION status
If the STATUS phase is already executed in the current I/O process, the
HDD performs as " → BUS FREE."
TASK COMPLETE message.
: Improbable combination
C141-C015