128K Sequential Read
Testing the ASR-72045 was challenging because its speeds are very hard to saturate. In a RAID 0 configuration the ASR-72405 delivers tremendous sequential speeds, higher than we have achieved from any other single slot solution. We configured our 16 SSDs into a RAID 0 with a stripe size of 256K.
We tested at QD256 with a 128K file size and achieved 6,640 MB/s. This speed was very consistent, with little variability during the test period.
The majority of read requests were served with the 4-6ms range, with 55% (or 53,899,281 I/Os) falling into that range. 24% (23,899,281 I/Os) fell into the 2-4ms range, and 16% (15,384,532 I/Os) fell into the 6-8ms range.
128K Sequential Write
Write speeds are the hardest aspect to test with a controller with so much speed on tap. It is important to note that we began with the SSDs freshly secure erased. The nature of SSDs leads to a descent into steady state, and from the test below, we can see that the SSDs hit the write cliff during our testing. This lower level of performance is due to the limitations of our hardware, and not any limitations from the ASR-72405 RAID controller.
We started out at 4,000 MB/s, and then the SSDs began to sink into their steady state performance. The sequential write speed of the C400's utilized for testing is 260MB/s each, and the write speed measured during the fresh condition represents perfect scaling from these SSDs. We simply do not have the required speed from our SSDs to saturate the sequential write speed of the ASR-72405, which tops out at 5,229MB/s.
The sequential write commands fell into a wide berth of latency, with 30% (16,348,896 I/Os) falling into the 4-6ms range, 28% (15,620,482 I/Os) into the 2-4ms range, and 14% (8,140,931 I/Os) coming in at 6-8ms.