Can you only partially use raid?

[n64man120]

I'd assume this will work perfectly fine, but I was wondering...
Can you put one hdd as OS/Apps, and then set 2 other drives in Raid1 for backup?
For some reason the back of my head is telling me the computer might want to raid it all or nothing, but I've never used raid so idk.

 

[The_Mage18]

Yes, that's possible. Your only limit to how you setup the drives in what arrays is how many drives your RAID controller supports. Nearly all newer RAID controllers will allow you to use a single drive as is without setting it up as a memeber of an array (look for JOBD, just a bunch of disks).