On Fri, 28 Jan 2005 10:59:58 -0500
Alex Turner <armtuk@gmail.com> wrote:
> At this point I will interject a couple of benchmark numbers based on
> a new system we just configured as food for thought.
>
> System A (old system):
> Compaq Proliant Dual Pentium III 933 with Smart Array 5300, one RAID
> 1, one 3 Disk RAID 5 on 10k RPM drives, 2GB PC133 RAM. Original
> Price: $6500
>
> System B (new system):
> Self Built Dual Opteron 242 with 2x3ware 9500S-8MI SATA, one RAID 1
> (OS), one 4 drive RAID 10 (pg_xlog), one 6 drive RAID 10 (data) on 10k
> RPM Raptors, 4GB PC3200 RAM. Current price $7200
>
> System A for our large insert job: 125 minutes
> System B for our large insert job: 10 minutes.
>
> There is no logical way there should be a 12x performance difference
> between these two systems, maybe 2x or even 4x, but not 12x
>
> Bad controler cards/configuration will seriously ruin your day. 3ware
> escalade cards are very well supported on linux, and work excellently.
> Compaq smart array cards are not. Bonnie++ benchmarks show a 9MB/sec
> write, 29MB/sec read on the RAID 5, but a 172MB/sec write on the
> 6xRAID 10, and 66MB/sec write on the RAID 1 on the 3ware.
>
> With the right configuration you can get very serious throughput. The
> new system is processing over 2500 insert transactions per second. We
> don't need more RAM with this config. The disks are fast enough.
> 2500 transaction/second is pretty damn fast.
I agree that badly supported or configured cards can ruin your
performance.
However, don't you think moving pg_xlog onto a separate RAID and
increasing your number of spindles from 3 to 6 on the data RAID would
also have a significant impact on performance, no matter what card was
used?
I'm not sure you can give all the credit to the card on this one.
---------------------------------
Frank Wiles <frank@wiles.org>
http://www.wiles.org
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