On Wed, Aug 17, 2011 at 1:55 PM, Ogden <li...@darkstatic.com> wrote: > > > What about the OS itself? I put the Debian linux sysem also on XFS but > haven't played around with it too much. Is it better to put the OS itself on > ext4 and the /var/lib/pgsql partition on XFS? > > We've always put the OS on whatever default filesystem it uses, and then put PGDATA on a RAID 10/XFS and PGXLOG on RAID 1/XFS (and for our larger installations, we setup another RAID 10/XFS for heavily accessed indexes or tables). If you have a battery-backed cache on your controller (and it's been tested to work), you can increase performance by mounting the XFS partitions with "nobarrier"...just make sure your battery backup works.
I don't know how current this information is for 9.x (we're still on 8.4), but there is (used to be?) a threshold above which more shared_buffers didn't help. The numbers vary, but somewhere between 8 and 16 GB is typically quoted. We set ours to 25% RAM, but no more than 12 GB (even for our machines with 128+ GB of RAM) because that seems to be a breaking point for our workload. Of course, no advice will take the place of testing with your workload, so be sure to test =)
