Backblaze uses this value as a failure indicator. Snapraid recommends replacing the disk if this value is greater than zero. Acronis states
Command Timeout S.M.A.R.T. parameter indicates a number of aborted operations due to hard disk timeout.
Recommendations
This is a critical parameter. Degradation of this parameter may indicate serious problems with power supply or an oxidized data cable. Urgent data backup and hardware replacement is recommended.
I have several drives with large Command Timeout values that I believe were the cause of faulty cabling. If the cause is not the drive itself, and those drives appear to be working fine, replacing them doesn’t make sense to me. Furthermore, I would imagine that a faulty backplane in a datacenter setup would result in a large number of drives having non-zero values and replacing them would be completely ineffective at resolving the issue.
I’m curious as to others’ thoughts on the usefulness of this value in assessing drive health.
All data is data.
Like tler, some attributes are more or less telling depending on the use case.
For a raid array using hardware controllers, the controllers might mark a disk as bad, and reject it on the off chance it is failing with a few things.
In a home setup/ single drive use case, the O/S can typically wait 100times longer for a response from a drive.
You are also on to something, in that BB or similar might dump 4-5 perfectly good drives before replacing a backplane, because that might be cheaper in time/resources than to troubleshoot.
But at the same time, there might be a drive issue.
So yes, investigate and poke around with and S.M.A.R.T error, and well done looking beyond the actual reported error to a possible root cause
Personally, I have drives that are nearing the end of their lives, but they still work fine for redundant scratch and stuff, so have them around.
