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.
We have another class of machine running on FusionIO IODrive2 MLC
cards in RAID-1 and 4 6 core non-HT CPUs. It's a bit slower (1366
versus 1600MHz Memory, slower CPU clocks and interconects etc) and it
can do about 5k tps and again, like the ther machine, no IO Wait, all
CPU bound. I'd say once you get to a certain level of IO Subsystem it
gets harder and harder to max it out.
I'd love to have a 64 core 4 socket AMD top of the line system to
compare here. But honestly both class of machines are more than fast
enough for what we need, and our major load is from select statements
so fitting the db into RAM is more important that IOPs for what we do.