Re: OT - 2 of 4 drives in a Raid10 array failed - Any chance of recovery?

On Tue, Oct 20, 2009 at 1:11 AM, Ow Mun Heng <ow.mun.heng@wdc.com> wrote:
> Sorry guys, I know this is very off-track for this list, but google hasn't
> been of much help. This is my raid array on which my PG data resides.
>
> I have a 4 disk Raid10 array running on linux MD raid.
> Sda / sdb / sdc / sdd
>
> One fine day, 2 of the drives just suddenly decide to die on me. (sda and
> sdd)
>
> I've tried multiple methods to try to determine if I can get them back
> online.
>
> 1) replace sda w/ fresh drive and resync - Failed
> 2) replace sdd w/ fresh drive and resync - Failed
> 3) replace sda w/ fresh drive but keeping existing sdd and resync - Failed
> 4) replace sdd w/ fresh drive but keeping existing sda and resync - Failed
>
>
> Raid10 is supposed to be able to withstand up to 2 drive failures if the
> failures are from different sides of the mirror.
>
> Right now, I'm not sure which drive belongs to which. How do I determine
> that? Does it depend on the output of /prod/mdstat and in that order?

Is this software raid in linux?  What does

cat /proc/mdstat

say?