We compare the different RAID arrays by calculating their performance rating using the following formula:

Performance = Total I/O (queue=1)/1 + Total I/O (queue=2)/2 + Total I/O (queue=4)/4 + Total I/O (queue=8)/8 + Total I/O (queue=16)/16 + Total I/O (queue=32)/32.

Once again the single hard disk drive is the slowest of all. RAID0 arrays got ranked according to the number of hard drives in them, and so did RAID5 arrays. However, RAID5 made of 8 HDDs is slower than RAID0 of 3 HDDs. The performance of RAID10 arrays of 6 and 4 HDDs are pretty high, while the 8 HDD array could have performed better.

Let’s see how the WriteBack caching algorithm of the controller affects its performance with 4-HDD arrays:

Switching to WriteThrough mode doesn’t change the overall situation, although the general performance rate drops down by 45% on average.