Performance in Intel IOMeter Sequential Read and Write Patterns

Now let’s pass over to sequential reading and writing. The array receives a stream of read/write requests with a request queue depth of 4. Every minute the size of the data block changes, so we can see the dependence of the linear read/write speed on the size of the data block by the end of the test session. The sequential read results (the dependence of the controller data transfer rate on the data block size) are listed in the following table:

Let’s take a look at the graphs showing the dependence of the array performance on the data block size:

The advantages of RAID 0 arrays made of a lot of hard disk drives start showing only for the large data blocks, i.e. when the controller can split large chunks of data into a few smaller ones and use HDDs in parallel. RAID 0 arrays look pretty good: they all reach their maximum performance with 64KB data blocks already (and the 2-HDD array shows its maximum speed with a 16MB data block). We can clearly see that the read speed of the array depends on the number of HDDs involved, and the 4-HDD array performs close to the maximum bus bandwidth (266MB/s).

RAID1 and RAID10 mirrored arrays turned out less attractive here. In most testmodes they are slower than a single HDD and a RAID 0 array of two HDDs respectively.