Now let’s have a look at the WebServer pattern, which is known for having no writes at all:

The major feature distinguishing these graphs from what we have just seen in FileServer pattern, is the fact that the single HDD graph and the ones for RAID 0 arrays start in the same point. The thing is that under linear workload RAID 0 arrays take advantage of their ability to make the HDDs work in parallel. The received request is simply sent to a corresponding drive and the HDDs work independently of one another (the requests data block is smaller than the stripe).

The performance drop you can see in case of large queue depth blocks processed by RAID 10 and RAID 1 arrays is a feature of the Intel SRCS14L controller, although I personally would regard it as a bug…

Just like in SequentialRead mode, the lazy writing doesn’t affect the performance in WebServer pattern in any way.

Again we suggest comparing the performance of different RAID arrays using our rating system. Considering all the workloads equally probable we will calculate the rating coefficient as the average controller performance under all types of workload:

The absence of writes changes the situation completely. RAID 10 array still manages to outperform RAID 0 array of four hard disk drives, however, since its performance drops down under heavy workload it yields to RAID 5 of four HDDs. RAID 5 array of three HDDs occupies the fourth place in this case. It was really interesting to see RAID 5 array of four drives outperform RAID 0 composed of the same four drives.