Originally posted by graphicgr8s raz-o I do a lot of PS work, have to it's my job. If you have enough ram you Photoshop won't be using swap files. Only time I ever have it go to a swap is when I am switching/using Indesign, Photoshop and Illustrator all open at once. I have 2 drives but they are mirrored so there is no real increase in swap writes. And yes since I do full color layout my files tend to get huge.
Is that not what I said in point 1? Even with RAID striping, you can still run into contention if the OS is swapping stuff out to the page file (this is mitigated a lot in vista and windows 7 as long as an app isn't idle). However, with mirroring, every time you write something twice every time you write it. Mirroring increases latency of writes until both writes are done.
Striping - speeds things up, increases chance of failure
Spanning - speed is the same, failure is worse, but not as bad as striping, looks like a big disk.
Mirroring - copies data to multiple drives on write. decreases failure rate (really failures will occur at same rate as a normal disk, but the mirror lets you repair said errors), and decreases speed.
Mirroring wouldn't affect the rate of writing to scratch either. Exceeding the memory allocated to an app, or in general running out of ram or meeting/failing to meet the caching criteria is what increases the frequency writing to scratch.