Let’s now see what the RAID5 and RAID10 arrays have to show.

The RAID5 arrays are slower at this load than the mirroring arrays. Of course, the performance of all the arrays is going down as the percentage of writes becomes higher, but we couldn’t have expected that the performance of the RAID1 would be near that of the three-disk RAID5.

At high percentages of read requests the RAID1 and RAID10 are faster due to the intellectual selection of the optimal (for the particular request) disk from the mirroring couple. But why are the RAID5 arrays so slow at writing?

Since we again do not see any big difference between the RAID5 made of different number of disks at high percentages of writes, we begin to suspect the XOR processor to be the weak link. The checksum calculations seem to be the bottleneck.

If we compare the mirroring RAID1 and RAID0 arrays with the single drive and the two-disk RAID0, respectively, we are going to see that like at linear load the mirroring arrays are faster when there’s high probability of a read requests and slower when there’s high probability of a write request.

The behavior of the arrays doesn’t change much at a queue of 256 requests.

Here we also offer the controller’s results at Write Policy = Write Through (click here to see the results ).