Pulsar XT.2 SAS Product Manual, Rev. B
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6.3.6
Drive Self Test (DST)
Drive Self Test (DST) is a technology designed to recognize drive fault conditions that qualify the drive as a
failed unit. DST validates the functionality of the drive at a system level.
There are two test coverage options implemented in DST:
1.
Extended test
2.
Short test
The most thorough option is the extended test that performs various tests on the drive and scans every logical
block address (LBA) of the drive. The short test is time-restricted and limited in length—it does not scan the
entire media contents, but does some fundamental tests and scans portions of the media.
If DST encounters an error during either of these tests, it reports a "diagnostic failed" condition. If the drive fails
the test, remove it from service and return it to Seagate for service.
6.3.6.1
DST failure definition
The drive will present a “diagnostic failed” condition through the self-tests results value of the diagnostic log
page if a functional failure is encountered during DST. The drive parameters are not modified to test the drive
more stringently, and the recovery capabilities are not reduced. All retries and recovery processes are enabled
during the test. If data is recoverable, no failure condition will be reported regardless of the recovery processes
required to recover the data.
The following conditions are considered DST failure conditions:
• Read error after recovery attempts are exhausted
• Write error after recovery attempts are exhausted
Recovered errors will not be reported as diagnostic failures.
6.3.6.2
Implementation
This section provides all of the information necessary to implement the DST function on this drive.
6.3.6.2.1
State of the drive prior to testing
The drive must be in a ready state before issuing the SEND DIAGNOSTIC command. There are multiple rea-
sons why a drive may not be ready, some of which are valid conditions, and not errors. For example, a drive
may be in process of doing a FORMAT UNIT, or another DST. It is the responsibility of the host application to
determine the “not ready” cause.
6.3.6.2.2
Invoking DST
To invoke DST, submit the SEND DIAGNOSTIC command with the appropriate Function Code (001b for the
short test or 010b for the extended test) in bytes 1, bits 5, 6, and 7.
