On Thu, Feb 11, 2010 at 4:29 AM, Bruce Momjian <br...@momjian.us> wrote: > Kevin Grittner wrote: >> Jesper Krogh <jes...@krogh.cc> wrote: >> >> > Sorry if it is obvious.. but what filesystem/OS are you using and >> > do you have BBU-writeback on the main data catalog also? >> >> Sorry for not providing more context. >> >> ATHENA:/var/pgsql/data # uname -a >> Linux ATHENA 2.6.16.60-0.39.3-smp #1 SMP Mon May 11 11:46:34 UTC >> 2009 x86_64 x86_64 x86_64 GNU/Linux >> ATHENA:/var/pgsql/data # cat /etc/SuSE-release >> SUSE Linux Enterprise Server 10 (x86_64) >> VERSION = 10 >> PATCHLEVEL = 2 >> >> File system is xfs noatime,nobarrier for all data; OS is on ext3. I >> *think* the pg_xlog mirrored pair is hanging off the same >> BBU-writeback controller as the big RAID, but I'd have to track down >> the hardware tech to confirm, and he's out today. System has 16 >> Xeon CPUs and 64 GB RAM. > > I would be surprised if the RAID controller had a BBU-writeback cache. > I don't think having xlog share a BBU-writeback makes things slower, and > if it does, I would love for someone to explain why.
I believe in the past when this discussion showed up it was mainly due to them being on the same file system (and then not with pg_xlog separate) that made the biggest difference. I recall there being a noticeable performance gain from having two file systems on the same logical RAID device even. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
