I re-installed Sabayon on to my main hard drive. I also have Arch installed on another hard drive. Grub can see Sabayon and Win 7 on the main hard drive but fails to detect Arch on the other. grub-mkconfig -o /boot/grub/grub.cfg doesn't help.
fdisk -l gives me this:
Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x357fae20
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 982439009 491218481 7 HPFS/NTFS/exFAT
/dev/sda2 982439936 983463935 512000 83 Linux
/dev/sda3 983463936 1953523711 485029888 8e Linux LVM
Disk /dev/sdb: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xf16d6536
Device Boot Start End Blocks Id System
/dev/sdb1 * 1 80324 40162 83 Linux
/dev/sdb2 80325 1140614 530145 82 Linux swap / Solaris
/dev/sdb3 1140615 16514819 7687102+ 83 Linux
/dev/sdb4 16514820 625137344 304311262+ 83 Linux
Disk /dev/mapper/vg_athena-lv_root: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders, total 104857600 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/vg_athena-lv_root doesn't contain a valid partition table
Disk /dev/mapper/vg_athena-lv_home: 434.5 GB, 434529894400 bytes
255 heads, 63 sectors/track, 52828 cylinders, total 848691200 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/vg_athena-lv_home doesn't contain a valid partition table
Disk /dev/mapper/vg_athena-lv_swap: 8422 MB, 8422162432 bytes
255 heads, 63 sectors/track, 1023 cylinders, total 16449536 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/vg_athena-lv_swap doesn't contain a valid partition table
How can I get Grub to detect Arch?
