Some thoughts on the performance of SSD RAID 0 arrays

Compressible Data Test

As shown in the previous page, we measured the performance at each configuration using CrystalDiskMark.
First, we set CrystalDiskMark to “All 0x00 Fill mode” to evaluate the performance of the array when dealing with compressible data.

In the sequential read test, the best performance was achieved with stripe sizes from 32 kiB to 128 kiB. The RAID array was between 61% and 107% faster than a single SSD. In the sequential write test, using a 128 kiB stripe size proved to be 8% faster than when using a 32 kiB stripe size, which was the slowest configuration. Here, the performance improvement was between 73% and 87% over a single SSD.

In the random read test with 512 kiB blocks, the best performance was with a stripe size of 64 kiB (75% faster than a single drive), and the worst was with a stripe size of 4 kiB (60% faster than a single SSD). In the random write test with 512 kiB blocks, the best performance was achieved with stripe size of 16 kiB, configuration that was 9% faster than using a stripe size of 32 kiB, which was the slowest configuration. The gain over a single drive was between 72 and 88 percent.

Surprisingly, in the random read test with 4 kiB blocks, there was no performance gain of using a RAID 0 array over a stand-alone SSD. Only with 128 kiB stripe size the result was significant, with an improvement of 24 percent. In the write test with 4 kiB blocks, a single drive reached higher performance than any RAID 0 configuration, being up to 41% faster.