Fujitsu MAA3182FC Series, Manual

Page: 278 / 327

C141-E054-02EN 5 - 1
CHAPTER 5 SENSE DATA AND ERROR RECOVERY
METHODS
5.1 Sense Data
5.2 INIT Error Recovery Methods (Recommended)
5.3 Disk 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.
5.1 Sense Data
When the IDD reports a CHECK CONDITION status, or in cases when some fatal error is detected
in connection with the FC interface, 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. Sense data are returned to the INIT at the same time as the status is sent in response
to the command.
5.1.1 Sense 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.
IMPORTANT
1) In the 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.