Thanks, Harm. I was reading more on RPM vs Gb/s ... and from my understanding RPMs wins as better for system drives.
Here's my dilema ... myAsus mobo has 6 sata 3Gb/s and 2 6Gb/s. Currently 5 3gbs satas are slotted for my raid5 (7200) and system drive (10K RPM).
Since I'd like to add onboard raid0 for media cache - my thought is to go with 2 6gbs 7200 rpm 320gb drives.
Then use the remaining 3gbs sata with a 7200 1Tb for exports drive.
Is this good logic?
Makes sense, but I would make sure that the export drive is the same brand/model as the ones in your raid5.
Raid5 using the on-board controller is very slow, so you may want to expand the raid to 5 drives to increase its speed and then you can use your export disk for that and get an external disk as export destination. First see if the on-board speed it good enough for your purposes, then you decide to go the expanded raid route or not.
To clarify my strategy, my raid5 4 disk array will be using an external raid controller and the onboard raid will drive the 2 smaller 6gbs at raid 0.
Drives are all WD ... which I just read you haven't had great luck with. Keep your fingers crossed.