Re: Best filesystem for a high load db

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.

--
Bill Moran
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