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CHAPTER 7 ERROR ANALYSIS
7.1 Sense Data Collection
7.2 Sense Data Analysis
This chapter explains in detail how sense data collected from an HDD is used for troubleshooting. Sense
data reflects an error in the HDD, and helps with troubleshooting.
7.1 Sense Data Collection
7.1.1 Sense data
When HDD posts a CHECK CONDITION status or detects a fatal error in the SCSI bus, the
current command or queued command is cleared. In such a case, the HDD generates sense data
about the command-issuing initiator. The initiator can read the sense data by issuing a REQUEST
SENSE command.
This HDD is equipped with sense data with a byte length of 48. Accordingly, Fujitsu
recommends collecting all 48-byte sense data when the host unit collects sense data.
Even if a transfer byte length that is shorter than the sense data length of the tested device is
specified, the command terminates normally. In this case, however, the initiator receives part of
the sense data, but the remaining part of the sense data is lost.
For details of the REQUEST SENSE command, refer to Subsection 3.1.15 “REQUEST SENSE
(15)” of the SCSI Logical Interface Specifications.
A sense key, additional sense code, and additional sense code qualifier, taken from various sense
data are repeated. Also in this chapter, troubleshooting is performed using these three codes.
Unless otherwise specified, "sense data" means the above three codes. When sense data is
represented as (x-xx-xx), the leftmost x is a sense key, the middle xx is an additional sense code,
and the rightmost x is an additional sense code qualifier.
7.1.2 Sense data format
Figure 7.1 shows the sense data format.
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