Is S.M.A.R.T. smart to use?

A few years ago I was told to avoid S.M.A.R.T. like the plague. The reasoning was that the stress the testing puts on the drive will actually cause it to fail.

Is this still the case? If not, what is a reasonable frequency to run tests? If I should still be avoiding it, what is a better way to monitor the health of my hard drives?

While S.M.A.R.T. certainly doesn't predict all failures, I worked in a computer repair shop for several years, and many times a S.M.A.R.T. error message was the first indication that a failure was about to occur, allowing me to save the customer's data before the drive died.

The technology itself does not stress the drive, it just keeps track of a number of indicators (full list here: http://en.wikipedia.org/wiki/S.M.A.R.T.) that could potentially lead to drive failure, such as:

• Read Error Rate
• Reallocated Sectors Count
• Spin Retry Count
• Uncorrectable Sector Count
• Power on Hours

The performance hit for S.M.A.R.T. is negligable, doesn't stress drives (the monitoring is passive), and can potentially warn you that you are about to lose all the pictures of your kids (or your MP3 collection or whatever is important on your Hard Drive).

In short, leave it on.

Besides passively logging performance counters and events, SMART provides an interface to initiate several types of self-tests performed by the drive and get their results later.

Some of these tests involve scanning of the entire platter surface while staying online and responding to host requests, so heavy I/O will cause a lot of head threshing.

I guess the latter is the source of the grave misconception you've been told. SMART is nice.