Chapter 4 SCSI Commands
SEND DIAGNOSTIC Command (1Dh)
DLT-S4 Interface Reference Guide
324
Table 179
SEND
DIAGNOSTIC
Command Data
—
Field Descriptions
Level 1 Test: Electronics
Test
4
Running a Level 1 test requires that a major portion of the controller
hardware and software be functioning properly. The Level 1 test is based
on the premise that full power-up testing is not necessary; therefore, it is
an extension of the power-on tests that the drive runs. The test verifies the
controller software Error Detection Code (EDC) and checks one queue
that much of the controller software uses by dequeuing and enqueuing
items. The test also runs a cache memory test. Finally, this test checks the
status of the servo subsystem by sending a
STATUS
command to the servo
and interpreting the results.
The Level 1 test does not attempt a
WRITE
or
READ
to or from the tape
medium. If an error occurs during the Level 1 test, the drive reports a
CHECK CONDITION
status and reports any errors that occurred in the
extended Sense Data bytes.
The Level 1 test has an execution time of approximately 5 seconds. See
table 180
for information on setting the
SEND DIAGNOSTIC
CDB fields to
select a Level 1 test.
Level 2 Test: Write / Read
Functionality Test
4
The Level 2 test performs the following actions:
1 Writes two tracks of data, one in each direction.
2 Rewinds the tape.
Field
Description
PF
Page Format. Must be set to 0 when the SelfTst bit is set
to 1.
Selftst
Self Test. Used with DevOfl and UnitOfl to specify the
type of testing to be done (see
table 180
for specific
information).
DevOfl
Device Offline. Used with Selftst and UnitOfl to specify
the type of testing to be done (see
table 180
for specific
information).
UnitOfl
Unit Offline. Used with Selftst and DevOfl to specify the
type of testing to be done (see
table 180
for specific
information).
Parameter
List Length
Indicates the number of bytes of parameter data that will
be sent to the drive. Must be 0 when the SelfTst bit is set
to 1.
