The benchmark methodology I described in previous posts, so let me jump directly to results.
The card is doing stable 380 MiB/sec level, but after around 4000 sec, as garbage collector kicks in, we see a performance drop to around 300 MiB/sec with some instability, which I will research in later charts.
It gives almost stable 370 MiB/sec throughput, with some strange small periodic drops.
To better understand response time ranges, we need to switch to synchronous IO and vary amount of threads.
We still see small hiccups in throughput and response times even for small amount of threads.
For 8 threads the 95% response time is 0.69ms.
So there is more or less stable performance only for 1 thread. For 2 or more, the throughput varies a lot from second to second. I draw boxplots, which show 25-50-75 percentiles. So there is no grow in throughput after 2 threads, and the result averages at 300 MiB/sec.
I am still interesting in asynchronous IO, as MySQL 5.5 uses async IO for writes. Maybe 8 threads in the first graph is too much and we should go with 1 thread?
So even with 1 async write thread the throughput jumps a lot in range 200 – 400 MiB/sec.
As conclusion, I should say that 300 MiB/sec level for random reads and writes is very decent result for SATA card. I think with this performance SATA is getting closer to level of PCIe cards. Of course PCIe still provides better numbers, but the question is how much MySQL can use. In his keynote Mark Callaghan mentioned that Fusion-io cards they use are highly underutilized.
With the performance variance we see it is a good question how does it affect MySQL performance, and I am going to run some MySQL workloads on these cards to understand it better.
If you are interested more in SSD and MySQL questions – I will be giving a webinary “MySQL and SSD” on May-9. It will be the same as my talk on Percona Live MySQL Conference 2012, if you did not attend my talk – you are welcome to join the webinar.
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