Re: Optimal settings for RAID controller - optimized for writes

On 20.2.2014 02:47, Scott Marlowe wrote:
> On Wed, Feb 19, 2014 at 6:10 PM, Tomas Vondra <tv@fuzzy.cz> wrote:
>> On 19.2.2014 19:09, Scott Marlowe wrote:
>
>>> Right now I'm testing on a machine with 2x Intel E5-2690s
>>> (http://ark.intel.com/products/64596/intel-xeon-processor-e5-2690-20m-cache-2_90-ghz-8_00-gts-intel-qpi)
>>> 512GB RAM and 6x600GB Intel SSDs (not sure which ones) under a LSI
>>
>> Most likely S3500. S3700 are not offered with 600GB capacity.
>>
>>> MegaRAID 9266. I'm able to crank out 6500 to 7200 TPS under pgbench on
>>> a scale 1000 db at 8 to 60 clients on that machine. It's not cheap,
>>> but storage wise it's WAY cheaper than most SANS and very fast.
>>> pg_xlog is on a pair of non-descript SATA spinners btw.
>>
>> Nice. I've done some testing with fusionio iodrive duo (2 devices in
>> RAID0) ~ year ago, and I got 12k TPS (or ~15k with WAL on SAS RAID). So
>> considering the price, the 7.2k TPS is really good IMHO.
>
> The part number reported by the LSI is: SSDSC2BB600G4 so I'm assuming
> it's an SLC drive. Done some further testing, I keep well over 6k tps
> right up to 128 clients. At no time is there any IOWait under vmstat,
> and if I turn off fsync speed goes up by some tiny amount, so I'm
> guessing I'm CPU bound at this point. This machine has dual 8 core HT
> Intels CPUs.

No, it's S3500, which is a MLC drive.

http://ark.intel.com/products/74944/Intel-SSD-DC-S3500-Series-600GB-2_5in-SATA-6Gbs-20nm-MLC

Tomas