| From: | Josh Berkus <josh(at)agliodbs(dot)com> |
|---|---|
| To: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: 8K recordsize bad on ZFS? |
| Date: | 2010-05-10 21:16:46 |
| Message-ID: | 4BE877BE.8000908@agliodbs.com |
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| Lists: | pgsql-performance |
> 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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