Quantum 10K II - page 308

Feature Descriptions
Quantum Atlas 10K II Ultra 160/m SCSI Hard Disk Drives 6-7
6.15 DIAGNOSTICS
The drive has extensive diagnostic capabilities, including those described below:
power-on self-test, periodic self-adjustments, and host diagnostics. Quantum uses
self-diagnostic tests and sense data tracking to manage drive errors, in addition to
logical block address (LBA) revectoring.
6.15.1 Power On Self Test (POST)
The disk drive performs a self-diagnostic test immediately at power up. Both the
Fault LED and a Busy LED briefly illuminate during spin-up as a lamp test.
If the drive passes the self-tests (and the spin-up jumper is installed), it spins up
and performs further diagnostics on the Head Disk Assembly (HDA). The drive
indicates “not ready” until the HDA tests are completed successfully.
The drive diagnostics test the following:
• RAM and ROM chips
• Buffer memory
• Gate array chips
• Read/write encoding circuits
• Basic servo functions
After a SELECTION TIME following power-on, the disk drive is able to respond with
appropriate status and sense data to the TEST UNIT READY, INQUIRY, and
REQUEST SENSE commands.
6.15.2 Periodic Self-Adjustments
During normal drive operation, certain periodic functions occur automatically so the
drive can verify and maintain the integrity of its operations and optimize
performance. The operations performed include those listed below.
• Move/Switch idle heads
• Adaptive seek profile calibration
• ROM checksum
Such periodic functions can make the drive appear to be active when no commands
are outstanding, because the drive appears to be seeking. Periodic calibrations occur
only after the drive has been inactive for 30 seconds.
NOTE
If a media access command is received during a calibration, the drive aborts
the calibration process and acts on the command.
If desired, calibrations can be suspended to reduce drive overhead by setting the
Manual Calibration bit in the (Vendor) Special Function Control page. If this is
done, manual calibrations can still be initiated by performing a REZERO UNIT
command.