On 09/13/2011 08:15 PM, Toby Corkindale wrote:
Hi,
Some months ago, I ran some (probably naive) benchmarks looking at how pgbench
performed on an identical system with differing filesystems. (on Linux).
Since then the kernel-level version of ZFS became usable, and there have been
improvements to btrfs, and no doubt various updates in the Linux kernel and
PostgreSQL that should help performance.
I ran the tests on Ubuntu 11.04 with Pg 9.0 first, then upgraded the system to
Ubuntu 11.10 (beta) with Pg 9.1 and ran them again.
The latter combination showed a considerable performance improvement overall -
although I didn't investigate to find out whether this was due to kernel
improvements, postgres improvements, or virtio improvements.
The results are measured in transactions-per-second, with higher numbers being
better.
Results:
ext4 (data=writeback,relatime):
natty: 248
oneiric: 297
ext4 (data=writeback,relatime,nobarrier):
natty: didn't test
oneiric: 1409
XFS (relatime):
natty: didn't test
oneiric: 171
btrfs (relatime):
natty: 61.5
oneiric: 91
btrfs (relatime,nodatacow):
natty: didn't test
oneiric: 128
ZFS (defaults):
natty: 171
oneiric: 996
Conclusion:
Last time I ran these tests, xfs and ext4 pulled very similar results, and both
were miles ahead of btrfs. This time around, ext4 has managed to get a
significantly faster result than xfs.
However we have a new contender - ZFS performed *extremely* well on the latest
Ubuntu setup - achieving triple the performance of regular ext4!
I'm not sure how it achieved this, and whether we're losing some kind of data protection
(eg. like the "barrier" options in XFS and ext4).
If ext4 has barriers disabled, it surpasses even ZFSs high score.
Oddly, ZFS performed wildly differently on ubuntu 11.04 vs 11.10b. I can't
explain this. Any ideas?
Cheers,
Toby
Did you test unplugging the power cable in the middle of a test to see which
would come back up?
-Andy
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