With most if not all RAID 1 the RAID is the size of the smaller drive. The rest of the space vanishes. This is NOT a bug. This has also been discussed before and please research why this happens. Remember that it's NOT A BUG. This was supposed to happen.

As to the drive that's only 250GB.

After I have everything ready for a disaster I would boot up my GPARTED bootable CD to look over the drives and see if there was a way to grow that partition.