>> No, it is not degraded, it's a clean 2-drive RAID5. I know it doesn't >> make much sense as it is ;-) the intent was to grow the array later, >> relying on mdadm's grow feature. Right now, I'm guessing that it >> operates like a RAID1 for all practical purposes. > > Actually No. If it is RAID-5 as you claim, then currently it is > effectively a RAID-0. > > RAID-5 is Striping with Distributed Parity and requires a *minimum* of > 3 disks. Two disks, regardless of how you got there, is considered a > degraded state. Actually, I need to retract those statements. A clean two disk RAID-5 array can be created and is actually very similar to a RAID-1 array. >From this thread: http://ubuntuforums.org/archive/index.php/t-566803.html --- If you're using just 2 disks in a non-degraded setup, then you'll have the following structure Drive1 Drive2 Block1: A1 P1 Block2: P2 B1 Block3: C1 P3 Block4: P4 D1 In this case, you're parity blocks will actually be identical to your non-parity blocks. This is because P1 is calculated as P1 = A1 XOR ?? Since there is no other block to XOR your bits with, md falls back to ?? = 0, and we all know that the XOR of 0 is the identity. That is, P1 = A1 XOR 0 == A1 --- I stand corrected. :-) -- Drew "Nothing in life is to be feared. It is only to be understood." --Marie Curie -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
