According to their website i dont think it will affect RAID, only software. (http://windows.microsoft.com/en-gb/windows-8/restore-refresh-reset-pc)
"Refresh your PC without affecting your files
If your PC isn't performing as well as it once did, and you don't know why, you can refresh your PC without deleting any of your personal files or changing your settings."
Warning
The applications that came with your PC or that you've installed from Windows Store will be reinstalled, but any applications that you've installed from other websites and DVDs will be removed. Windows puts a list of the removed applications on your desktop after refreshing your PC.
To refresh your PC
Swipe in from the right edge of the screen, tap Settings, then tap Change PC settings.
(If you're using a mouse, point to the top-right corner of the screen, move the mouse pointer down, click Settings, then click Change PC settings.)
Under PC settings, tap or click General.
Under Refresh your PC without affecting your files, tap or click Get started.
Follow the instructions on the screen.
Removing everything and reinstalling Windows
If you want to recycle your PC, give it away or just start afresh, you can reset it completely.