| From: | Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz> |
|---|---|
| To: | Strahinja Kustudić <strahinjak(at)nordeus(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: 8xIntel S3500 SSD in RAID10 on Dell H710p |
| Date: | 2014-12-10 03:55:14 |
| Message-ID: | 5487C422.2000306@catalyst.net.nz |
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| Lists: | pgsql-performance |
On 10/12/14 12:28, Strahinja Kustudić wrote:
> * These tests are with the H710p controller set to write-back (WB) and
> with adaptive read ahead (ADRA). I ran a few tests with
> write-through (WT) and no read ahead (NORA), but the results were worse.
That is interesting: I've done some testing on this type of card with 16
(slightly faster Hitachi) SSD attached. Setting WT and NORA should
enable the so-called 'fastpath' mode for the card [1]. We saw
performance improve markedly (300MB/s random write go to 1300MB/s).
This *might* be related to the fact that 16 SSD can put out more IOPS
than the card can actually handle - whereas your 8 S3500 is probably the
perfect number (e.g 8*11000 = 88000 which the card can handle ok).
[1] If you make the change while there are no outstanding background
operations (array rebuild etc) in progress (see
http://www.flagshiptech.com/eBay/Dell/poweredgeh310h710h810UsersGuide.pdf).
Cheers
Mark
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