From: Mark Kirkwood <markir@paradise.net.nz>
To: Miguel <mmiranda@123.com.sv>
Cc: pgsql-performance@postgresql.org
Subject: Re: freebsd/softupdates for data dir
Date: Tue, 04 Apr 2006 14:10:25 +1200
Message-ID: <4431D591.30500@paradise.net.nz> (raw)
In-Reply-To: <4431C4B4.4090300@123.com.sv>
References: <4431C4B4.4090300@123.com.sv>
Miguel wrote:
> Hi, reading the archives i cant find a clear answer about softupdates in
> freebsd, is it recommended to enable it for the data directory?
>
There is a pretty good article about softupdates and journelling here:
http://www.usenix.org/publications/library/proceedings/usenix2000/general/full_papers/seltzer/seltze...
and in the freebsd docs here:
http://www.freebsd.org/doc/handbook/configtuning-disk.html
Postgres does not do a lot of file meta-data operations (unless you do a
*lot* of CREATE/DROP INDEX/TABLE/DATABASE), so the performance gains
associated with softupdates will probably be minimal.
I've always left them on, and never had any issues...(even after
unscheduled power loss - which happened here yesterday). As I understand
it, the softupdate code reorders *metadata* operations, and does not
alter data operations - so the effect of fysnc(2) on a preexisting file
is not changed by softupdates being on or off.
Cheers
Mark
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To: pgsql-performance@postgresql.org
Cc: markir@paradise.net.nz, mmiranda@123.com.sv
Subject: Re: freebsd/softupdates for data dir
In-Reply-To: <4431D591.30500@paradise.net.nz>
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