| From: | Jeff <threshar(at)torgo(dot)978(dot)org> |
|---|---|
| To: | Henrik <henke(at)mac(dot)se> |
| Cc: | david(at)lang(dot)hm, Luke Lonergan <LLonergan(at)greenplum(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Filesystem benchmarking for pg 8.3.3 server |
| Date: | 2008-08-11 14:01:57 |
| Message-ID: | 2DBD3E73-D9E5-4DFA-832F-3FD53480B284@torgo.978.org |
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| Thread: | |
| Lists: | pgsql-performance |
On Aug 11, 2008, at 5:17 AM, Henrik wrote:
> OK, changed the SAS RAID 10 to RAID 5 and now my random writes are
> handing 112 MB/ sek. So it is almsot twice as fast as the RAID10
> with the same disks. Any ideas why?
>
> Is the iozone tests faulty?
does IOzone disable the os caches?
If not you need to use a size of 2xRAM for true results.
regardless - the test only took 10 seconds of wall time - which isn't
very long at all. You'd probably want to run it longer anyway.
>
> iozone -e -i0 -i1 -i2 -i8 -t1 -s 1000m -r 8k -+u -F /database/iotest
>
> Children see throughput for 1 random writers = 112074.58 KB/sec
> Parent sees throughput for 1 random writers = 111962.80 KB/sec
> Min throughput per process = 112074.58 KB/sec
> Max throughput per process = 112074.58 KB/sec
> Avg throughput per process = 112074.58 KB/sec
> Min xfer = 1024000.00 KB
> CPU utilization: Wall time 9.137 CPU time 0.510 CPU
> utilization 5.58 %
>
--
Jeff Trout <jeff(at)jefftrout(dot)com>
http://www.stuarthamm.net/
http://www.dellsmartexitin.com/
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