pgsql + chroot + RAID5 performance?

Hi all,

I'm developing a website with a postgresql backend.
I thought to put postgres on a server with RAID5 (as the risk of
downtime has to be minized as much a possible).

I also would like to make it run in a chroot environment.

Are there big performance hits? How can I configure postgres to limit
the consequences to make it run in a chroot environment? What is your
reaction when you read RAID5?

Thanks in advance for your help :-)

Raph