Fujitsu MAP3735 Sense data analysis and error recovery methods, Sense data error classification

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).

5.2.2Sense 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.

				Table 5.3	Sense data error classification	(1 of 4)
	K*	C*	Q*		Outline of Error		L*	Recovery Method
								(See Table 4.4.)
	0	x	x	No sense data showing the error contents are held.			None	4
	1	13	00	Sync byte not found for data field			Need	8
		15	xx	Positioning error
		17	xx	Recovered error without ECC
				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.
	1	37	00	Rounded parameter			None	9
				The IDD's rounding processing was applied to the
				MODE SELECT parameters specified by the INIT.
	2	04	01	Logical unit not ready			Need**	10**
				The logical unit specified by the command is in a
				state where it cannot be accessed.
			02	Logical unit not ready
	2	04	04	Logical unit not ready, format in progress			None	11
				The logical unit specified by the command is
				currently being formatted, so access is impossible.
	3	0C	03	Peripheral device write fault			Need	7
				Unrecovered write offtrack error
				The maximum number of write offtrack retries was
				reached when AWRE = 0.
* K: Sense Key				C: Sense Code
	Q: Sub-sense code			L: Logging Necessary? (shown in Section 5.2.3)

**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.

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