Comment 279 for bug 1289977

dpkg-reconfigure asks you which drive or drives you want grub to be installed to ( and reinstalled to during future upgrades ). If you only have one drive then the choice is simple. If you have more than one, then generally sda is the one your system boots from, but if you have reconfigured your bios to boot from another drive, then that is the drive you should use. If in doubt, it doesn't hurt anything to just install it to all of your drives.