From: Marko Ristola <Marko.Ristola@kolumbus.fi>
Cc: pgsql-performance@postgresql.org
Subject: Re: extremly low memory usage
Date: Sat, 20 Aug 2005 14:17:54 +0300
Message-ID: <43071162.6050405@kolumbus.fi> (raw)
In-Reply-To: <EFA54B85-504E-453A-972D-A7DD0E144763@drivefaster.net>
References: <1124331108.27881.96.camel@bluejay.goodinassociates.com>
<EA4219B9-E2B0-4756-ABF2-D84F245FDFB5@torgo.978.org>
<1124386761.27881.119.camel@bluejay.goodinassociates.com>
<4304CB77.4070403@arbash-meinel.com>
<1124470109.27881.152.camel@bluejay.goodinassociates.com>
<43061472.2080201@arbash-meinel.com>
<6.2.3.4.0.20050819140714.05c181e8@pop.earthlink.net>
<43063196.9000001@arbash-meinel.com>
<1124485299.27881.192.camel@bluejay.goodinassociates.com>
<EFA54B85-504E-453A-972D-A7DD0E144763@drivefaster.net>
Dan Harris wrote:
> From my recent experiences, I can say ext3 is probably not a great
> choice for Pg databases. If you check the archives you'll see
> there's a lot of discussion about various journalling filesystems and
> ext3 usually(always?) comes up on the bottom as far as performance
> goes. If you insist on using it, I would at least recommend the
> noatime option in fstab and using data=writeback to get the faster
Based on my knoledge, Ext3 is good with keeping filesystem integrity AND
data integrity while
pressing the reset button.
However, by selecting data=writeback, you gain more speed, but you risk the
data integrity during a crash: Ext3 garantees only filesystem integrity.
This means with database transaction logs: The last transactions are not
guaranteed to be written into the hard drives during a hardware reset,
meaning of a loss of some committed transactions.
Reiserfs is known to do things this false way also.
Is there a way with a Reiserfs filesystem to fulfill both
filesystem AND data integrity requirements nowadays?
See for example "man mount" to see the effects of data=journal,
data=ordered(default) and
data=writeback for Ext3. Only the writeback risks data integrity.
Ext3 is the only journaled filesystem, that I know that fulfills
these fundamental data integrity guarantees. Personally I like about
such filesystems, even though it means less speed.
Marko Ristola
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To: pgsql-performance@postgresql.org
Cc: Marko.Ristola@kolumbus.fi
Subject: Re: extremly low memory usage
In-Reply-To: <43071162.6050405@kolumbus.fi>
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