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
