[OpenIndiana-discuss] dc s3700 for pool devices -- poor performance

[Jim Klimov]

On 2013-10-09 21:45, Jason Matthews wrote:
>
>
> Do we have anyone using the s3700 in their pools with any kind of scale?
>
> I picked up an eval from dell using an r820 4x4650L, 576GB of RAM, and 8 dc
> s3700 drives on OI151a8. Testing with filebench and the random write
> personality indicates one device pushes 14k 8kb write operations/second. I
> really thought it would turn out more but the news gets worse.
> ...
> Are there any ideas out there?

Not many, but the subject is interesting. Note that I am a noob in this
area, only planning to play with my first SSDs ever sometime soon, but
otherwise I can only guess (educated by this and other mailing lists).

On one hand, you did not indicate which s3700 devices you use here?
The lower capacity models have lower performance even according to
the specs (100gb very noticeably, 200gb by a margin), so maybe you're
hitting something here.

On another hand, there were recommendations from various sides regarding
the high performance of SSDs in general, and that there should be more
HBAs per storage device than is usual for HDDs (for example, Oracle ZFS
SA have about 4 SSD slots among dozens of HDD slots). I guess the PCI
bus(es) where these HBAs are attached can also get saturated, so check
if your two HBAs are on different buses (there should probably be a few
on server-grade hardware).

You wrote that performance degrades with amount of devices, but the
provided table is not as scary - it maybe flatlines (asymptotically
reaching your bottleneck ceiling) and degrades per-device, but at
least does not become smaller for the overall pool.

I hope these ramblings lead somewhere at least :)
//Jim