Re: Best filesystem for a high load db

From: Maila Fatticcioni <mfatticcioni(at)mbigroup(dot)it>
To: Bill Moran <wmoran(at)potentialtech(dot)com>, Christoph Berg <cb(at)df7cb(dot)de>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Best filesystem for a high load db
Date: 2014-11-26 10:16:51
Message-ID: 5475A893.9090202@mbigroup.it
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On 11/25/2014 05:54 PM, Bill Moran wrote:
> On Tue, 25 Nov 2014 17:27:18 +0100 Christoph Berg <cb(at)df7cb(dot)de>
> wrote:
>
>> Re: Bill Moran 2014-11-25
>> <20141125111630(dot)d05d58a9eb083c7cf80ed9f8(at)potentialtech(dot)com>
>>> Anything with a journal is a performance problem. PostgreSQL
>>> effectivly does its own journalling with the WAL logs. That's
>>> not to say that there's no value to crash recovery to having a
>>> journalling filesystem, but it's just to say that our
>>> experience showed journaling filesystems to be slower. That
>>> rules out ext4, unless you disable the journal. I seem to
>>> remember ext4 with journalling disabled being one of the faster
>>> filesystems, but I could be remembering wrong.
>>
>> If you are using a non-journalling FS, you'll be waiting for a
>> full fsck after a system crash. Not sure that's an improvement.
>
> It's an improvement if: a) You're investing in high-quality
> hardware, so the chance of a system crash is very low. b) The
> database is replicated, so your plan in the event of a primary
> crash is to fail over to the backup anyway.
>
> If both of those are in place (as they were at my previous job)
> then the time it takes to fsck isn't an issue, and taking action
> that causes the database to run faster when nothing is wrong can be
> considered.
>
> Obviously, the OP needs to assess the specific needs of the product
> in question. Your point is very valid, and I'm glad you brought it
> up (as a lot of people forget about it) but sometimes it's not the
> most important factor.
>

Thank you a lot to have shared with me your experiences.
Indeed we will have two servers in cluster with high quality hardware
so a fsck restore shouldn't be a big problem.
I will analize the xfs option as well and then I will decide.

Thank you again,
Maila Fatticcioni

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