Re: Filesystem benchmarking for pg 8.3.3 server

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@jefftrout.com>
http://www.stuarthamm.net/
http://www.dellsmartexitin.com/