Walt Mankowski on 18 Jun 2013 04:58:30 -0700

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Re: [PLUG] PLUG West - Monday June 17, 2013 - Linux Filesystems and Benchmarking, presented by K.S. Bhaskar (7pm at FIS in Malvern)

On Tue, Jun 18, 2013 at 06:32:08AM -0400, Rich Freeman wrote:
> On Tue, Jun 18, 2013 at 12:51 AM, JP Vossen <jp@jpsdomain.org> wrote:
> >
> > Work stuff aside, 11 out of 13 machines I just checked are running ext3, the
> > other 2 are ext4.  Guess I'll need to look into that.
> >
> One little tip though - put /var/lib/mysql on ext3 and not ext4.
> Ext4, mysql, and barrier support combine to give very poor
> performance.  MySQL recommends just disabling barriers, which IMHO is
> right up there with how their motto used to be "who needs ACID?"
> Moving just mysql to ext3 results in a fairly dramatic performance
> increase (in fact, I should probably stop allocating so much RAM for
> it now).
> Otherwise, yes, ext4 is probably your best all-around option until
> btrfs is production-ready.  I don't like xfs since it can't be shrunk
> - I like my filesystems to be flexible (preferably with online
> resizing).

My understanding is that the main reason ext3 is so much faster with
mysql (and also with sqlite3) is that barriers are turned off by
default, while in ext4 they're turned on by default.  Given the choice
between ext3 (barriers off by default) vs ext4 (barriers turned off by
choice) isn't ext4 still the better all-around option?


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