Pages

Wednesday, September 8, 2010

RAID01 Vs RAID10

So what is the difference between RAID01 and RAID10?


>>>>When we are dealing with RAID01 we are actually implementing RAID0 first then RAID1 on it. Ok little bit confused?
Let me put it in this way RAID0 is nothing but stripeset writing of data and RAID1 is Mirring of data on to disks.For example lets take 8 disks, so first we are writing whole data on 4 disks then we are mirring it on to remaining disks.
Where as in RAID10 we are first mirring disk and then striping data on mirrered disks
In general RAID01 is "a mirrior of 2 strips" and RIAD10 is "a single strip on mirrered disks"

So here one more question arises... which one is good?
RAID10 is good, the difference is that the chance of system failure with two drive failures in a RAID 0+1 system with two sets of drives is (n/2)/(n - 1) where "n" is the total number of drives in the system. The chance of system failure in a RAID 1+0 system with two drives per mirror is 1/(n - 1). So, using the 8 drive systems shown in the diagrams, the chance that loosing a second drive would bring down the RAID system is 4/7 with a RAID 0+1 system and 1/7 with a RAID 1+0 system.