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Re: Samsung 32GB SATA SSD tested

From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: "Jeffrey Baker" <jwbaker(at)gmail(dot)com>
Cc: "Pgsql performance" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Samsung 32GB SATA SSD tested
Date: 2008-07-23 20:10:53
Message-ID: dcc563d10807231310h46b15e0fgb0c06ffe0ee815a6@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Wed, Jul 23, 2008 at 1:57 PM, Jeffrey Baker <jwbaker(at)gmail(dot)com> wrote:
> On Tue, Jul 22, 2008 at 5:32 PM, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> wrote:
>> On Tue, Jul 22, 2008 at 6:04 PM, Jeffrey W. Baker <jwbaker(at)gmail(dot)com> wrote:
>>
>>> Strangely the RAID controller behaves badly on the TPC-B workload.  It
>>> is faster than disk, but not by a lot, and it's much slower than the
>>> other flash configurations.  The read/write benchmark did not vary when
>>> changing the number of clients between 1 and 8.  I suspect this is some
>>> kind of problem with Areca's kernel driver or firmware.
>>
>> Are you still using the 2.6.18 kernel for testing, or have you
>> upgraded to something like 2.6.22.  I've heard many good things about
>> the areca driver in that kernel version.
>
> These tests are being run with the CentOS 5 kernel, which is 2.6.18.
> The ioDrive driver is available for that kernel, and I want to keep
> the software constant to get comparable results.
>
> I put the Samsung SSD in my laptop, which is a Core 2 Duo @ 2.2GHz
> with ICH9 SATA port and kernel 2.6.24, and it scored about 525 on R/W
> pgbench.

From what I've read the scheduler in 2.6.24 has some performance
issues under pgsql.  Given that the 2.6.18 kernel driver for the areca
card was also mentioned as being questionable, that's the reason I'd
asked about the 2.6.22 kernel, which is the one I'll be running in
about a month on our big db servers.  Ahh, but I won't be running on
32 Gig SATA / Flash drives. :)  Wouldn't mind testing an array of 16
or so of them at once though.

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