RAID 1 / disk error / Offline uncorrectable sectors
wmoran at potentialtech.com
Mon Jun 16 12:56:27 UTC 2008
In response to Zbigniew Szalbot <z.szalbot at lc-words.com>:
> A couple of days ago smartd let me know about a disk problem.
> Jun 14 01:13:38 relay kernel: ad12: FAILURE - READ_DMA48
> status=51<READY,DSC,ERROR> error=40<UNCORRECTABLE> LBA=374468863
> Jun 14 01:13:38 relay kernel: ar0: WARNING - mirror protection lost.
> RAID1 array in DEGRADED mode
> Jun 14 01:14:19 relay kernel: ad12: WARNING - WRITE_DMA taskqueue
> timeout - completing request directly
> Jun 14 01:14:19 relay kernel: ad12: WARNING - WRITE_DMA48 freeing
> taskqueue zombie request
> Jun 14 01:37:38 relay smartd: Device: /dev/ad12, 1 Currently
> unreadable (pending) sectors
> Jun 14 01:37:38 relay smartd: Device: /dev/ad12, 1 Offline
> uncorrectable sectors
> If I do smarctl -a /dev/ad12 I get
> 197 Current_Pending_Sector 0x0012 100 100 000 Old_age Always
> - 1
> 198 Offline_Uncorrectable 0x0010 100 100 000 Old_age
> Offline - 1
> My understanding is that RAID 1 no longer works because of this error.
> There is a bad sector on HD (Offline uncorrectable sectors) and the best
> we can do is replace the drive? Does it make sense to try to turn RAID 1
> on ignoring this error (however, this is done in BIOS so the machine
> would have to be taken down in order to do that)? It seems serious
> enough for me not to ignore it but then I know close to nothing about HDs.
Replace the hard drive. Every modern hard drive keeps extra space available
to "remap" bad sectors. This happens magically behind the scenes without
you ever knowing about it. Once you've hit "uncorrectable" errors, it means
your re-mappable sectors are used up, and that means the drive is on its
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