Q: can/should I run a disk defrag software on a raid 1 set up? can/should I run a disk defrag software on a raid 0 set up?

A: It is possible to do so, there isn't anything preventing it. Should you? Well, that's part of the greater Should You Defrag At All debate.

A: If you are using Windows Vista, Windows 7 or Windows 2008/R2, it possibly already does it in the background.
Personally, I would and there shouldn't be any more risk compared to doing it on a regular hard drive.
However, take a look first at the RAID driver/software (if it comes with any) - usually only on high-end hardware raid solutions, see if it has a defrag utility/feature built in.
