Sense Data Analysis And Error Recovery Methods; Sense Data Error Classification - Fujitsu MAP3147 Scsi Logical Interface Specifications

Sense Data Error Recovery Methods
The cause of this error is the occurrence of an unrecoverable error on the SCSI bus, the occurrence
of a serious protocol error, etc. For details concerning the causes of errors, see Chapter 3, "SCSI Bus
Error Recovery Processing" in Chapter 3 of the "SCSI Physical Specifications." When this error is
detected, the INIT should issue the REQUEST SENSE command and gather sense data then judge
the error recovery method according to the contents of the sense data (see Section 4.2.2).
5.2.2

Sense data analysis and error recovery methods

The INIT can judge the procedure for error recovery by analyzing the contents of the sense data
fetched by the REQUEST SENSE command. Table 5.3 the classifications of error information
displayed in the sense data are shown and in Table 5.4, the procedures for error recovery
recommended for the INIT to execute are shown. The error recovery procedure which can be
executed by the INIT will differ depending on the system's condition, so the optimum processing
procedure should be selected for the user system with reference to the following descriptions.
K* C* Q*
0 x x No sense data showing the error contents are held.
1 13 00 Sync byte not found for data field
15 xx Positioning error
17 xx Recovered error without ECC
1 37 00 Rounded parameter
2 04 01 Logical unit not ready
02 Logical unit not ready
2 04 04 Logical unit not ready, format in progress
3 0C 03 Peripheral device write fault
* K: Sense Key
Q: Sub-sense code
** Except within the time required for the disk drive to reach the ready state (approx. 20 seconds) after the
power has been switched on, or after a start instruction has been executed by the START/STOP UNIT
command.
5 - 14
Table 5.3 Sense data error classification (1 of 4)
Outline of Error
These errors are errors detected during accessing of
the disk media, but they are recovered from
through the IDD's retry processing. However,
when "1" is specified in the DTE flag in the
MODE SELECT parameters, the command may
not necessarily be executed until it is completed.
The IDD's rounding processing was applied to the
MODE SELECT parameters specified by the INIT.
The logical unit specified by the command is in a
state where it cannot be accessed.
The logical unit specified by the command is
currently being formatted, so access is impossible.
Unrecovered write offtrack error
The maximum number of write offtrack retries was
reached when AWRE = 0.
C: Sense Code
L: Logging Necessary? (shown in Section 5.2.3)
Recovery Method
L*
(See Table 4.4.)
None 4
Need 8
None 9
** 10**
Need
None 11
Need 7
C141-E167