From: Yeb Havinga <yebhavinga@gmail.com>
To: Greg Smith <greg@2ndquadrant.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Testing Sandforce SSD
Date: Mon, 26 Jul 2010 21:42:03 +0200
Message-ID: <4C4DE50B.1060102@gmail.com> (raw)
In-Reply-To: <4C4DAAE8.3060501@2ndquadrant.com>
References: <4C4A9452.9070100@gmail.com>
<4C4B1F84.5030306@2ndquadrant.com>
<4C4C83DF.3010703@gmail.com>
<4C4C8CCC.7080406@gmail.com>
<alpine.DEB.2.00.1007261045470.20471@aragorn.flymine.org>
<4C4D6396.5020707@gmail.com>
<4C4DAAE8.3060501@2ndquadrant.com>
Greg Smith wrote:
> Yeb Havinga wrote:
>> Please remember that particular graphs are from a read/write pgbench
>> run on a bigger than RAM database that ran for some time (so with
>> checkpoints), on a *single* $435 50GB drive without BBU raid controller.
>
> To get similar *average* performance results you'd need to put about 4
> drives and a BBU into a server. The worst-case latency on that
> solution is pretty bad though, when a lot of random writes are queued
> up; I suspect that's where the SSD will look much better.
>
> By the way: if you want to run a lot more tests in an organized
> fashion, that's what http://github.com/gregs1104/pgbench-tools was
> written to do. That will spit out graphs by client and by scale
> showing how sensitive the test results are to each.
Got it, running the default config right now.
When you say 'comparable to a small array' - could you give a ballpark
figure for 'small'?
regards,
Yeb Havinga
PS: Some update on the testing: I did some ext3,ext4,xfs,jfs and also
ext2 tests on the just-in-memory read/write test. (scale 300) No real
winners or losers, though ext2 isn't really faster and the manual need
for fix (y) during boot makes it impractical in its standard
configuration. I did some poweroff tests with barriers explicitily off
in ext3, ext4 and xfs, still all recoveries went ok.
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To: pgsql-performance@postgresql.org
Cc: yebhavinga@gmail.com, greg@2ndquadrant.com
Subject: Re: Testing Sandforce SSD
In-Reply-To: <4C4DE50B.1060102@gmail.com>
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