>>> On Thu, Nov 8, 2007 at 2:14 PM, in message <200711082114.36788.dfontaine@xxxxxxxxxxxx>, Dimitri Fontaine <dfontaine@xxxxxxxxxxxx> wrote: > The Dell 2900 5U machine has 10 spindles max, that would make 2 for the OS > (raid1) and 8 for mixing WAL and data... not enough to benefit from the > move, > or still to test? >From our testing and various posts on the performance list, you can expect a good battery backed caching RAID controller will probably eliminate most of the performance difference between separate WAL drives and leaving them on the same RAID array with the rest of the database. See, for example: http://archives.postgresql.org/pgsql-performance/2007-02/msg00026.php Ben found a difference of "a few percent"; I remember seeing a post from someone who did a lot of testing and found a difference of 1%. As stated in the above referenced posting, it will depend on your workload (and your hardware) so it is best if you can do some realistic tests. -Kevin ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
