iTunes 11.1.5 versus S.M.A.R.T. hard drive sensor

Question

After I installed a bigger startup drive in my Mac Pro, I renamed the prior startup drive and use it to keep my media contents, including my iTunes media folder. I work that drive hard, doing video transcodes and such, and it doesn't have a problem, EXCEPT that when itunes is using it, especially if it is editing meta tags, it will FREQUENTLY hang, then declare that a S.M.A.R.T. sensor has stopped responding. Shortly after, the drive will disappear from the desktop and the system will berate me that I shouldn't disconnect disks without dismounting them.

The system message says that if it is just a slow sensor, I should disable monitoring.

So, the two questions are: How do I fix iTunes? And how do I stop monitoring that sensor.

Answer 1

Your disk either has bad sectors or is dying in some way (could be the SATA controller, the disk firmware controller, or the moving parts themselves). I wouldn't recommend disabling SMART. SMART is generally pretty good at knowing what it's talking about. If it's warning you that there's a problem and the drive is getting unmounted, that's usually a sign that the disk is going bad. It may only fail on certain patterns of access, so don't assume that just because you can push a lot of data through it while video transcoding, that it's perfectly fine.

Back up your data ASAP, then run a SMART short test; if the short test fails, replace the drive. If the short test passes, run a long test; if the long test passes, you probably just need to search for bad blocks and disable them so the filesystem won't try to use them. If the long test fails, you'll still probably want to replace the drive.

You can try this SMART tool to see if it will help you diagnose the problem or run tests on the drive. Ignore the program author's advice of running it "weekly" -- there's no need to run it so often unless you are closely monitoring the suspected failure of a device. I'd suggest not playing with fire: if you have a disk that has come up as problematic at least once according to SMART, you should really stop trying to use it, and just replace it. To do otherwise invites data loss, and it can happen at any time, or even lead to silent corruption (data gets messed up but the OS doesn't tell you about it, until you find out later that your music/videos/whatever have garbage in them).