4 ms·
In my experience, SMART doesn't detect anything of value. 95% of my disk failures are: - Seek time gets very high (>80%). - Drive drops dead and won't respond
by ianhowson 7y ago
In my experience, SMART doesn't detect anything of value. 95% of my disk failures are:
- Seek time gets very high (>80%).
- Drive drops dead and won't respond
SMART doesn't detect either of these.
Setting an alert on seek times > 30ms has been by far the best predictor of drive failure. If the seek times go over ~400ms then other components start complaining about slow/missing I/O, but by that point you've already gone crazy because your array is unusably slow.
If a drive develops bad sectors SMART will report it, but that's rare enough that I don't bother watching for it. It's a non-event with ZFS because of the checksumming. These drives never have one random error; they start raising hundreds in the space of minutes, and that's the moment you replace the drive.