Re: Reinstalling GRUB on RAID array
Look at this reference for reinstalling grub 2: https://help.ubuntu.com/community/Grub2#Reinstalling GRUB 2
Some further explanation. When you have your Ubuntu installed to a raid partition and are booting on the raid array, as it appears you are, the root is the raid partition you are installed to and the boot loader has to be written to the raid root drive. The installer usually tries to write the boot loader to a hard disk (sda,sdb, etc) rather than to the raid root. The nomenclature for these locations are found in /dev/mapper. After you have mounted your installed file system to /mnt as per the instructions, then the root-directory will be /mnt and the target for the boot loader will be /dev/mapper/<yourOverallRaidArrayName> as it now appears in /mnt/dev/mapper (<yourOverallRaidArrayName> will be the first so-called symbolic link preceeding the individual raid partitions). I hope this is enough to get you going. Post if you need more help.
12.10 Quantal w/grub2/Mint13 installed on raid0, Gigabyte AMD MB, AMD 64x4 CPUs at 3.2GHz, 16 GB ram, HD7770 ATI video, dual boot win7 on 64gb ssd and win8 on 1Tb SATA raid. 13.04 installed on raid0 and ssd