Fujitsu MAN3367, MAN3735, MAN3184 specifications Sense Data, Sense data format

CHAPTER 5 SENSE DATA ERROR RECOVERY METHODS

5.1Sense Data

5.2INIT Error Recovery Methods (Recommended)

5.3Disk Drive Error Recovery Processing

In this chapter, the configuration and contents of sense data reported to the INIT (initiator) when an error occurs, etc., key information for interpreting error states, recommended procedures for error recovery processing that should be executed by software in the INIT and error recovery processing executed internally by the IDD are described. Furthermore, see Chapter 3, “SCSI Bus Error Recovery Processing” in the “SCSI Physical Interface Specifications” concerning recovery processing for errors detected in operations on the SCSI bus.

5.1Sense Data

When the IDD reports a CHECK CONDITION status, or in cases when some fatal error is detected in connection with the SCSI bus, and as a result, the command that is currently being executed, or the commands in the stack are cleared, it generates sense data for the INIT that issued that command. The INIT can fetch the sense data by issuing a REQUEST SENSE command.

5.1.1Sense data format

The IDD’s sense data is in the so-called “Expanded Sense Data” format. The expanded sense data format supported by the IDD is shown in Figure 5.1.

Notes:

1.In the SCSI specifications, each device is permitted to define whatever it chooses after byte 18 of the expanded sense data, and the length and format differ for each device. The length of expanded sense data is displayed in the sense data, so by analyzing the sense data which it receives, the INIT can know its effective length.

2.In the REQUEST SENSE command, even if a Transfer byte length that is shorter than the length of the sense data supported by the device which is the object of the command, the command will terminate normally, but in that case, some of the sense data only will be received and the remaining information will be lost. Sufficient caution should be exercised with regard to the devices connected to the INIT and all the sense data of those devices should be read.

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