From: Marinos Yannikos <mjy@geizhals.at>
To: pgsql-performance@postgresql.org
Subject: Re: postgresql random io test with 2 SSD Kingston V+100 500GB in (software) Raid1
Date: Fri, 22 Apr 2011 23:43:58 +0200
Message-ID: <4DB1F69E.1000305@geizhals.at> (raw)
In-Reply-To: <BANLkTim0YuRG=6=SqYjutsKHJ5JSx+dg1Q@mail.gmail.com>
References: <BANLkTim0YuRG=6=SqYjutsKHJ5JSx+dg1Q@mail.gmail.com>
Am 19.04.2011 11:15, schrieb Laurent Laborde:
> Soft RAID1 (md)
> ext3
We have experimented a bit with Postgres and ext3 (with and without Linux
software RAID1) and have found that since somewhere after 2.6.18, it has been
prohibitively slow and causing high latencies during buffer flushes. You will
probably see a significant improvement with ext4 (mkfs.ext4, not just remount as
ext4, which is also possible).
Also, you need to make sure that your blocks are properly aligned with SSDs,
that might explain low random I/O performance. See
http://www.nuclex.org/blog/personal/80-aligning-an-ssd-on-linux and
http://www.ocztechnologyforum.com/forum/showthread.php?54379-Linux-Tips-tweaks-and-alignment&p=3...
for example.
Regards,
Marinos
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Subject: Re: postgresql random io test with 2 SSD Kingston V+100 500GB in (software) Raid1
In-Reply-To: <4DB1F69E.1000305@geizhals.at>
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