Re: Dell Perc/6

From: Tore Halset <halset(at)pvv(dot)ntnu(dot)no>
To: Dave Cramer <pg(at)fastcrypt(dot)com>
Cc: Craig James <craig_james(at)emolecules(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Dell Perc/6
Date: 2008-02-13 19:45:01
Message-ID: 5238B6D3-B026-4BAA-A7BA-3392405E597B@pvv.ntnu.no
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On Feb 13, 2008, at 12:06, Dave Cramer wrote:

>
> On 13-Feb-08, at 5:02 AM, Tore Halset wrote:
>
>> Hello.
>>
>> I think I started that discussion. We ended up buying a Dell 2900
>> with PERC 6/i and 10 * 145GB SAS 3,5" 15KRpm discs. 6 of the SAS
>> discs are in a raid 10 for the database, 2 in a mirror for the wal
>> and the last 2 in a mirror for the OS. We get 350MB/s writing and
>> 380MB/s reading to/from the raid 10 area using dd. The OS is Ubuntu
>> and the filesystem for the raid 10 is ext3.
>>
> Wow that's fantastic. Just to be sure, did you make sure that you
> read and wrote 2x memory to take the cache out of the measurement ?
>
> Dave
>

The box have 16GB of ram, but my original test file was only 25GB.
Sorry. Going to 33GB lowered the numbers for writing. Here you have
some samples.

% sh -c "dd if=/dev/zero of=bigfile bs=8k count=4000000 && sync"
32768000000 bytes (33 GB) copied, 103.722 seconds, 316 MB/s
32768000000 bytes (33 GB) copied, 99.669 seconds, 329 MB/s

% time dd if=bigfile of=/dev/null bs=8k
32768000000 bytes (33 GB) copied, 85.4235 seconds, 384 MB/s
32768000000 bytes (33 GB) copied, 85.4628 seconds, 383 MB/s

Regards,
- Tore.

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