I appreciate opportunity Jos van Dongen from Tholis Consulting gave me. He granted me access to servers with 8 attached Intel X-25M 80GB MLC cards. The cards attached to 2 Adaptec 5805 raid controllers, with 4 cards per controller.
The cost of setup is 8 x 260$ (X-25M) + 2×500$ (Adaptec 5805) = ~3000$.
Available space varies in depends on raid setup from 300GB to 600GB.
The logical comparison is to compare results with FusionIO 320GB MLC card, so I will copy results from FusionIO 320GB MLC benchmarks.
For benchmarks I used sysbench fileio benchmark.
All raw results are available on Percona benchmarks wiki, there I will highlight most interesting points.
Couple words on tested setups. We used two configurations:
I should highlight I do not see usage in production for RAID0, as in my opinion SSD cards
are not reached enough level of reliability yet (see comments to post FusionIO 320GB MLC benchmarks), however I put results here to show theoretical maximal results.
So let’s start with random reads:
I’d say SSDs show comparable results with FusionIO on 16+ threads, however on 4-8 threads difference is significant. On SSD you can get 160MB/sec for 4 threads and 260MB/sec for 8 threads.
There couple things to note (beside SSD is doing much worse than FusionIO).
1. Something is wrong with scaling random writes in this setup. It is point for research,
I think there some serialization in Linux software raid or Linux scheduler or on Adaptec hardware level.
2. Cards connected in hardware raids show worse results than card connected as single devices (you can see results on https://www.percona.com/docs/wiki/benchmark:ssd:start, in summary table, randwr rows)
3. For cards connected in hardware raids, DEADLINE performs much worse than CFQ.
– For sequential reads you can get pretty decent results from SSD (230MB/sec on 4+ threads)
– Cards connected in hardware raid is doing much better
– DEADLINE outperforms CFQ here (which is different from random writes)
– Software raid0 performed pretty bad, so I chosen to show hardware-raid0 results
I’d say sequential writes is hard task for both SSDs and FusionIO, it does not scale well.
You may want to look into another options if your load requires sequential writes (e.g. like I
put InnoDB transactional logs on rotation based drives instead of SSD in my InnoDB on FusionIO benchmarks).
So in summary I can say