There is no simple answer to your question. It CAN be --or you can NOT use a drive in the RAID array and set it as the system disk volume in which case windows will not be a part of the RAID array.
Is this typical? It depends on who you talk to.
Some network admins use an entirely different computer running windows or windows server to connect to another computer that actually houses the array.
The upside of NOT including the OS into the Array is that if something goes wrong with windows and for whatever reason you have to reinstall - you can do so without touching data in the array. But your system will still be down while your reinstalling windows. If you have say .. RAID 6 you can have up to 2 drives fail and still be operating (albeit possibly slower)
The downside - one of the whole reasons for a RAID array is for redundancy. Not having windows installed on a drive as part of the RAID array does not give you any benefit of redundancy (which is one of the whole purposes behind the array.
~as a note - RAID is not meant to be a backup it is typically used as a (file server) where you are providing access to files for possibly hundreds or thousands of users.
And finally .. I am not a RAID expert. I know just enough to know I as a home user do not need raid, however I have been around computers long enough to drive other people crazy asking them questions about RAID.
Edited by YeahBleeping, 18 May 2015 - 12:47 PM.