[CentOS] question on software raid
Jeremy Sanders
jeremy at jeremysanders.net
Mon Apr 4 09:17:49 UTC 2011
Scott Silva wrote:
> Could it be that the bad sectors so far have been in unused areas? Once a
> drive runs out of sectors to map corrections to, I would really think
> about replacing it.
This advice is so often repeated by people on lists. This is a pretty normal
function of modern hard drives. The drive needs to reallocate the bad
sectors. It does not mean that the drive is failing unless there have been a
large number of sectors requiring reallocation or it keeps happening often.
Have a look at this to fix them for normal drives without raid:
http://smartmontools.sourceforge.net/badblockhowto.html
Linux raid will rewrite the block if it is in the raided part of the disk.
You can force a scrub doing this (md0 is the raid device).
echo check > /sys/block/md0/md/sync_action
Check /proc/mdstat and dmesg for status.
You should be doing this weekly to identify bad blocks, so check your
crontab.
Jeremy
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