I am no expert, but have been asking them a bunch and I think your missing a key concept.
The data is best on several drives. I could be completely off, but if I understood (I just finished doing the same kind of thing minus several databases) you want your WAL on fast drives in raid 1 and your data (as many drives as you can use) on raid 10 (can be slower drives , but I saw you already have a bunch of 15k drives). So you may get best performance just using one database rather then several smaller ones on mirrored data drives. Keep in mind if you go with ES4 (I am using AS4) and postgres 8 you can add spindles and move hard hit tables to their own spindle. Again I am no expert; just thought I would echo what I was informed. I ended up using 2 15k drives in raid 1 for my WAL and 4 10k drives for my data in raid 10. I ended up using links to these from the original install of postgres on the raid 5, 4 15k drives inside the server itself. I believe this gives me three separate raid arrays for my install with logs and such on the raid 5, data on the raid 10 and wal on the raid 1. I am in the testing and conversion phase and have found it very fast. I used a 4 processor Dell 6550, but think from what I have been told your computer would have been a better choice (CPU wise). I am not using fibre but do have a 14 drive powervault which I split to have the 15k's on one side and the 10k's on the other. So I am using both channels of the controller. I have been told for me to get best performance I should add as many 10k drives to my data array as I can (but this was all I had in my budget). I have room for 3 more drives on that side of the powervault. Best of luck on your project. Joel ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org