Re: [SPAM?] Re: PG8 Tuning

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/