On 09/24/2010 07:50 PM, Digimer wrote:
> Raid 10 requires 4 drives. First you would make two RAID 0 arrays, then
> create a third array that is RAID 1 using the two RAID 0 arrays for it's
> devices.
>
> With only two drives, your option is RAID 1 (mirroring - proper
> redundancy) or RAID 0 (striping only - lose one drive and you lose *all*
> data).
>
>
That's 0+1 not 1+0.
And don't do it that way.
If you have a single drive failure with RAID 0+1 you've lost *all* of
your redundancy - one more failure and you are dead. If you create two
RAID1 sets and then strip them into a RAID0 you get pretty much the same
performance and space efficiency characteristics, but if you have a
drive failure you still have partial redundancy. You could actually take
a *second* drive failure as long as it was in the other RAID1 pair. With
4 drives raid0+1 can only survive 1 drive failure. With 4 drives in raid
1+0 you can survive an average of 1.67 drive failures.
--
Benjamin Franz
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