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Increasing reallocated sectors count: how to check hardware
Hello!
My ReadyNAS have detected massive increasing amount of reallocated sectors at one of 2 my mirrored HDDs. I pulled the HDD out to run some tests. S.M.A.R.T analysis detected reallocated sectors too (I believe ReadyNAS just uses S.M.A.R.T counters to detect these errors). But further surface tests did not find any problems, and HDD reseted it's S.M.A.R.T counter of reallocated sectors to zero then. I put the HDD back into the NAS, and the counter started to progress rapidly.
I believe something is wrong with a corresponding bay of the NAS and I want to check it. Can I correct errors at the HDD once again and just swap my mirrored drives then without putting my data at risk? Is it nesessary to hold disk's positions at bays?
Re: Increasing reallocated sectors count: how to check hardware
Hello, Stephen. Thank you for the reply. I haven't tried write tests yet and I understand that the most probable cause of those errors is HDD. I have no option to backup my data due to some reasons. This is the primary concern for not taking anything destructive. So, is it ok to swap HDDs in bays as the first step?
I have no option to backup my data due to some reasons. This is the primary concern for not taking anything destructive. So, is it ok to swap HDDs in bays as the first step?
Without a backup, you do risk data loss if a second drive fails.
I wouldn't swap the HDDs around. Though I don't see any way it can be the bay, if I am wrong you'd simply damage another different hard drive. That could end up being destructive.
Re: Increasing reallocated sectors count: how to check hardware
Sector re-allocation is entirely internal to the HDD. Nothing in the NAS can cause it. Command time-outs, on the other hand, can be the result of something odd in the NAS (and SMART.will detect and store them).
I have had a couple similar drives where manufacturer's tools said that the drive was OK but the NAS did not like it. In every case, return to the NAS resulted in more errors. I have wondered if the drive orientation might be a factor, as my USB dock has a different orientation than the NAS. But a drive with problems in one orientation and not in another is still a drive with problems that needs replacement.
But further surface tests did not find any problems,
Did you do the destructive write test, or only read tests? I've had drives which pass the read tests, but which fail on the write-zeros test.
It's hard to envision a failure mode of the bay that would cause the drive to increase its reallocated sector count.
Hello, Stephen. You were completely right. I managed to back my data up and proceeded with further tests. HDD did successfully pass read tests (again!) with nice clean SMART after that. But it failed succeeded write tests showing me 5K+ reallocated sectors:-) The reason is obviously HDD, just like you said. Thank you for help!
