Grub install devices & Software RAID

Server has a software RAID 1 (sda+sdb) configured as /dev/md0 device.

Later system upgrade was launched and grub updated. Now it promped to select grub unstall devices from the list to finish update:

- /dev/sda
- /dev/sdb
- /dev/md0

What items should be selected in case of RAID 1?

Update. fdisk tells:

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1           59343       60801    11719417+  fd  Linux raid autodetect

/dev/sda2   *           1       59342   476664583+  fd  Linux raid autodetect

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1           59343       60801    11719417+  fd  Linux raid autodetect
/dev/sdb2   *           1       59342   476664583+  fd  Linux raid autodetect

Answer

You should install GRUB to both /dev/sda and /dev/sdb, so that both devices are bootable. You want this so that the system will still boot if the first drive which the BIOS boots off fails.