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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?
gpn12buy wrote:
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.
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gpn12buy wrote:
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. 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?
gpn12buy wrote:
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.
The next step is to replace the disk.
StephenB wrote:
gpn12buy wrote: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!
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