You would have to quantify 'performance' more.
If you mainly do photo work, that's a different set of writing parameters than say needing to capture video data streams for an hour straight to the RAID unit.
RAID 5 will definitely give you redundancy like RAID1 will (parity versus mirroring) but will give you spanning capability (the ability to put data on more than 1 drive without needing a 1:1 mirror of each data drive). For many applications, the write performance hit isn't really that bad. For things that write all the time, yes, you will notice a hit.
Once you put the photos on the unit, the 'writing' part is done except for 'saving' changes to them, correct? I would think in that type of role, you will not be pounding the storage unit often enough to have the slower write of raid5 make that big of a difference (maybe a tiny fraction of a second on a multi-MB file). Add in write caching of the OS, and you may not even notice it at all. It's very subjective, but the rule is usually: Heavy constant near real-time writing of large data streams RAID5 = SUCKS. Random not so often writes: somewhere between 'not so bad' and 'pretty decent'
I follow ya. And yes, photo archiving and processing is quite a bit different from video or audio.
But...I will be doing considerable copying and moving, plus many of the utilities I run constantly scan for new images to archive, rename, and copy.
The overall system will probably be setup like this:
C Drive: I will upgrade to a Raptor II 72GB when I can afford it
36GB Raptor #1 (old one) will probably be used as a Photoshop Scratch Drive
36GB Raptor #2 (old one) will probably be used as gaming drive
3 - 500GB (Raid ??) hard drives used for photography processing & archiving, and utility/files storage.
I guess I'll just have to try out the various RAID setups and see what seems to work best for the weird way Photo processing is done. While it's not as intesive as video, the indexing/renaming/archiving does tax a system a bit.
Hell, I'm just excited to have a new PC! My video died on me 3 times last night while reading through the Paul thread, and it's very frustrating to have to reboot the system over and over and hope the video comes back !