On Aug 11, 2005, at 12:58 PM, Jeffrey W. Baker wrote:
> Like Mr. Stone said earlier, this is pure dogma. In my experience,
> xlogs on the same volume with data is much faster if both are on
> battery-backed write-back RAID controller memory. Moving from this
> situation to xlogs on a single normal disk is going to be much
> slower in
> most cases.
>
This does also point one important point about performance. Which is
a touch unfortunate (and expensive to test): Your milage may vary on
any of these improvements. Some people have 0 problems and
incredible performance with say, 1000 shared_bufs and the WAL on the
same disk.. Others need 10k shared bufs and wal split over a 900
spindle raid with data spread across 18 SAN's...
Unfortunately there is no one true way :(
The best bet (which is great if you can): Try out various settings..
if you still run into problems look into some more hardware.. see if
you can borrow any or fabricate a "poor man"'s equivalent for testing.
--
Jeff Trout <jeff@jefftrout.com>
http://www.jefftrout.com/
http://www.stuarthamm.net/
