On Mon Jan 31, 2011 at 01:32:06PM -0200, Roberto Spadim wrote:
> rewriting..
> using raid10 or raid01 you will have problems if you lose 2 drives too...
> if you lose two raid 1 devices you loose raid 1...
> see:
>
> disks=4
> RAID 1+0
> raid1= 1-2(A) ; 3-4(B); 5-6(C)
> raid0= A-B-C
> if you lose (A,B or C) your raid0 stop
>
> RAID 0+1
> raid0= 1-2-3(A) ; 4-5-6(B)
> raid1= A-B
> if you lose (1,4 OR 1,5 OR 1,6 OR 2,4 OR 2,5 OR 2,6 OR 3,4 OR 4,5 OR
> 4,6) your raid0 stop
>
> using raid1+0 or raid0+1 you can't lose two disks...
>
Yes you can - it just depends which disks. With the 6-disk case you can
lose a maximum of 3 drives, though only a single drive failure will
definitely not cause total array failure. For RAID1+0 your 2-drive
failure cases are only 1,2 OR 3,4 OR 5,6 - any other pairing will not
break the overall array. For RAID0+1 there's 9 failure cases as you
point out (except the last two should be 3,5 and 3,6).
Cheers,
Robin
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