Re: Poor performance of btrfs with Postgresql

On Thu, Apr 21, 2011 at 2:22 AM, Toby Corkindale
<toby(dot)corkindale(at)strategicdata(dot)com(dot)au> wrote:
> I've done some testing of PostgreSQL on different filesystems, and with
> different filesystem mount options.
>
> I found that xfs and ext4 both performed similarly, with ext4 just a few
> percent faster; and I found that adjusting the mount options only gave small
> improvements, except for the barrier options. (Which come with a hefty
> warning)
>
> I also tested btrfs, and was disappointed to see it performed *dreadfully* -
> even with the recommended options for database loads.
>
> Best TPS I could get out of ext4 on the test machine was 2392 TPS, but btrfs
> gave me just 69! This is appalling performance. (And that was with nodatacow
> and noatime set)
>
> I'm curious to know if anyone can spot anything wrong with my testing?
> I note that the speed improvement from datacow to nodatacow was only small -
> can I be sure it was taking effect? (Although cat /proc/mounts reported it
> had)
>
> The details of how I was running the test, and all the results, are here:
> http://blog.dryft.net/2011/04/effects-of-filesystems-and-mount.html
>
> I wouldn't run btrfs in production systems at the moment anyway, but I am
> curious about the current performance.
> (Tested on Ubuntu Server - Maverick - Kernel 2.6.35-28)

your nobarrier options are not interesting -- hardware sync is not
being flushed. the real numbers are in the 230 range. not sure why
brtfs is doing so badly -- maybe try comparing on single disk volume
vs raid 0?

merlin