Yesterday, David Best posted this question at Oracle-L:
If you had 8 disks in a server what would you do? From watching this list I can see alot of people using RAID 5 but i'm wary of the performance implicatons. (http://www.miracleas.com/BAARF/)
I was thinking maybe RAID 5 (3 disks) for the OS, software and
backups. RAID 10 (4 disks + 1 hot spare) for the database files.
I do have some thoughts about it.
There are four dimensions in which I have to make considerations as I answer this question:
Just about everybody understands at least a little bit about #1: the reason you bought 8 disks instead of 4 or 16 has something to do with how many bytes of data you're going to store. Most people are clever enough to figure out that if you need to store N bytes of data, then you need to buy N + M bytes of capacity, for some M > 0 (grin).