[mythtv-users] Why RAID 5 stops working in 2009

John Drescher drescherjm at gmail.com
Thu Oct 23 14:08:27 UTC 2008


>> Erm, if it's raid 6, wouldn't you need 3 drives to fail for it to kill
>> you?
> The way I understand RAID-6, the failure would have to be:
>
> 1 dead drive
> 1 URE on another drive
> 1 URE on yet another drive in the same stripe as the above URE
>
Highly unlikely and preventable. I mean you can have both hardware and
software check the drives every once and awhile so you if it finds
drives with UREs (bad sectors that can not be read - drive should have
fixed them on the first read that it detected a problem)  it will kick
the bad drive from the array then.

Also even in this unlikely case with mdadm you should be able to copy
the bad drives to new drives and force the arrays to sync even with
the missing data. I am not sure if hardware controllers allow you to
sync disks that have problems like this.


John


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