All Solaris installation methods, including Solaris Live Upgrade, now use the findroot command for specifying which disk slice to boot on an x86 based system. Previously, the root command, root (hd0.0.a), was used to explicitly specify which disk slice to boot. This information is located in the menu.lst file that is used by GRUB. The most common form of the entry in the menu.lst file is:
findroot (rootfs0,0,a) kernel$ /platform/i86pc/kernel/$ISADIR/unix module$ /platform/i86pc/$ISADIR/boot_archive
The findroot command has the ability to discover the targeted disk, irrespective of the boot device. In addition, the findroot command provides enhanced support for booting systems with ZFS roots, as well as those with UFS roots. In addition to the findroot command, the name of a signature file on the slice, (<mysign>, 0, a) is now provided. The boot signature is located in the /boot/grub/bootsign directory on the system. The name of the signature file varies, depending on the installation method that is used.
For more information, see Implementation of the findroot Command in System Administration Guide: Basic Administration.