Avago Technologies 3ware 9650SE-12ML (Channel) - Manual (Page 242)

3DM 2 Reference
230 3ware SAS/SATA RAID Software User Guide, Version 9.5.1
Self-test Schedules
Unlike scheduling of rebuilds and verifies, scheduling of self-tests is always
followed. To disable self-tests you either remove all schedule times, or
uncheck the tests listed in the Tasks column.
Two self-tests can be scheduled:
Upgrade UDMA mode. (Only applicable to PATA drives.) This test checks
the speed at which data transfer to drives is occurring, to see if the UDMA
mode can be increased. (If you are already running at the fastest UDMA
mode, then this self-test has no effect.)
The UDMA mode can become downgraded in the event that cable CRC errors
are encountered, requiring multiple retries to read sectors. In severe cases, the
UDMA mode may be downgraded from ATA 150 to ATA 133, to ATA 100, to
66, to 33.
This check is also done every time the system is booted.
Check SMART Thresholds. This test checks to see whether SMART
thresholds have been exceeded.
The SMART thresholds indicate when a drive is likely to fail, based on the
number of errors that have been recorded through SMART (Self-Monitoring,
Analysis and Reporting Technology).
If any of the disk drives have detected a “threshold exceeded” condition, then
an AEN is logged to the 3DM Alarms page. Moreover, if anything unusual is
found during any self-test, it will be logged as an Alarm.
Note: Only the checked tasks will be run during the scheduled times. If none of the
tasks are checked, self-tests will never run, even if you have scheduled time slots
set.