Can you go into some more detail on how you set up ZFS on these systems? Robert Treat conjecture: xzilla.net consulting: omniti.com On Tue, Sep 13, 2011 at 10:56 PM, Andy Colson <andy@xxxxxxxxxxxxxxx> wrote: > 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 > > -- > Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
