What is SMART?
If a failure is likely
to occur to hard drives, S.M.A.R.T. makes a status report available so that
the host can prompt the user to back up data on the failing drive. However,
not all failures can be predicted. S.M.A.R.T.
predictability is limited to the attributes the drive can monitor which are
selected by the device manufacturer based on the attribute’s ability to
contribute to the prediction of degrading or fault conditions.
Although attributes are drive specific, a variety of typical characteristics
can be identified:
• head flying height
• data throughput performance
• spin-up time
• re-allocated sector count
• seek error rate
• seek time performance
• spin try recount
• drive calibration retry count
Infortrend's Implementations
with SMART technologies
SMART is supported on hard drives that comply with ANSI-SCSI
Informational Exception Control (IEC) document X3T10/94-190 standard.
Disable:
Disable S.M.A.R.T.-related functions
Detect Only:
S.M.A.R.T. function enabled, commands will be issued to enable all drives' S.M.A.R.T.
function, if a drive predicts a problem, the subsystem will report the problem
in the form of an event log.
Perpetual Clone:
S.M.A.R.T. function enabled, commands will be issued to enable all drives' S.M.A.R.T.
function. If a drive predicts a problem, controller will report in the form
of an event log. Controller will clone the drive if there is a Dedicated/Global
spare available. The drive with predicted errors will not be taken off-line,
and the clone drive will still behave as a standby drive.
If the drive with predicted errors fails, the clone drive will take over immediately.
Under the circumstance that the problematic drive is still working and another
drive in the same logical drive should fail,
the clone drive will resume the role of a standby spare and start to rebuild
the failed drive immediately. This is to prevent a fatal drive error if yet
another drive should fail.
Clone + Replace:
Controller will enable all drives' S.M.A.R.T. function. If a drive predicts
a problem, controller will report in the form of event log. Controller will
then clone the problematic drive to a standby spare and take the problematic
drive off-line as soon as the cloning process is completed.
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