Filesystems, Disks and Memory

We just purchased a MOD30 disk array strage system.
We have 15 drives and 2 hot spares.
We're running a database app with 8 data sets.
I'm trying to get the best i/o speed out of my disk configuration.
Right now I have 3 raid5 arrays setup. This seems to offer the same performance as having the datafiles on separate hard drives with Raid1.
I distributed the data files evenly across the 3 raids.
Does anyone know what would make for the optimum config for reading? We run a lot of queries that take a long time to run through the database. I'm looking for faster searches.

Any thoughts?

What type of database?
We had informix on a raid5 set and performance was very poor. we mirrored our disks and make sure they were not on the same bus.
seemed to help.