Hardware Reference
In-Depth Information
Drives with S.M.A.R.T. monitor a variety of attributes that vary from one manufacturer
to another. Attributes are selected by the device manufacturer based on their capability to
contribute to the prediction of degrading or fault conditions for that particular drive. Most
drive manufacturers consider the specific set of attributes being used and the identity of
those attributes as vendor specific and proprietary.
Some drives monitor the floating height of the head above the magnetic media. If this
height changes from a nominal figure, the drive could fail. Other drives can monitor dif-
ferent attributes, such as ECC circuitry that indicates whether soft errors are occurring
when reading or writing data. Some of the attributes monitored on various drives include
the following:
• Head floating height
• Data throughput performance
• Spin-up time
• Reallocated (spared) sector count
• Seek error rate
• Seek time performance
• Drive spin-up retry count
• Drive calibration retry count
Each attribute has a threshold limit that determines the existence of a degrading or fault
condition. These thresholds are set by the drive manufacturer, can vary among manufac-
turers and models, and can't be changed.
Thebasicrequirements forS.M.A.R.T.tofunctioninasystemaresimple:Youjustneeda
S.M.A.R.T.-capable HDD and a S.M.A.R.T.-aware BIOS orhard disk driver foryourpar-
ticular OS. If your BIOS does not support S.M.A.R.T., utility programs are available that
can support it on a given system. Some of these include Norton Utilities from Symantec,
DiskCheckup from PassMark Software, and Acronis Drive Monitor.
When sufficient changes occur in the monitored attributes to trigger a S.M.A.R.T. alert,
the drive sends an alert message via an IDE/ATA or a SCSI command (depending on the
type of HDD you have) to the hard disk driver in the system BIOS, which usually reports
the problem during the POST the next time the system boots.
If you want more immediate reporting, you can run a utility that queries the S.M.A.R.T.
status of the drive, such as the programs listed earlier. The first thing to do if you receive
a S.M.A.R.T. warning is to back up all the data on the drive. I recommend you back up to
new media and do not overwrite previous backups you might have, just in case the drive
fails before the new backup is complete.
