From: Josh Berkus <josh@agliodbs.com>
To: pgsql-performance@postgresql.org
Subject: Re: 8K recordsize bad on ZFS?
Date: Mon, 10 May 2010 14:16:46 -0700
Message-ID: <4BE877BE.8000908@agliodbs.com> (raw)
In-Reply-To: <j2w407d949e1005101301r9a1c0f7dk9995279fcd7c26a8@mail.gmail.com>
References: <4BE4ABC9.6040106@agliodbs.com>
<AANLkTim6rVYoAZaspbEnsyE9LPmWGXWe4Van40Snldoj@mail.gmail.com>
<4BE852CE.9020802@agliodbs.com>
<hs9ltj$c8q$1@dough.gmane.org>
<4BE85ED3.4010008@agliodbs.com>
<j2w407d949e1005101301r9a1c0f7dk9995279fcd7c26a8@mail.gmail.com>
> That still is consistent with it being caused by the files being
> discontiguous. Copying them moved all the blocks to be contiguous and
> sequential on disk and might have had the same effect even if you had
> left the settings at 8kB blocks. You described it as "overloading the
> array/drives with commands" which is probably accurate but sounds less
> exotic if you say "the files were fragmented causing lots of seeks so
> our drives we saturated the drives' iops capacity". How many iops were
> you doing before and after anyways?
Don't know. This was a client system and once we got the target
numbers, they stopped wanting me to run tests on in. :-(
Note that this was a brand-new system, so there wasn't much time for
fragmentation to occur.
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com
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To: pgsql-performance@postgresql.org
Cc: josh@agliodbs.com
Subject: Re: 8K recordsize bad on ZFS?
In-Reply-To: <4BE877BE.8000908@agliodbs.com>
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