I have a Power Edge 2900 with a Perc6i and 6-250gb drives. 1 drive is bad and another is showing in a foreign state. I tried to find replacement drives of the same size and I'm unable to do so. I can find 750gb drives. Will the array rebuild with a larger drive installed?  If I purchase 2 can I use one as a replacement for the bad drive and allocate the other as a hot spare? 

If not can I purchase 2 and create and additional array and virtual disk with the new drives without affecting the original array?