Booting Multiple Boot Environments

If your system has more than one OS installed on the system, you can boot from these boot environments for both SPARC and x86 platforms. The boot environments available for booting include Solaris Live Upgrade inactive boot environments.

• Starting with the Solaris 10 10/08 release for a SPARC based system, you can boot a ZFS root file system in a ZFS pool. For ZFS root pools, you can list the available boot environments with the boot command with the -L option. You can then choose a boot environment and use the OBP boot command with the -Z option to boot that boot environment. The -Z option is an alternative for the luactivate command that is also used to boot a new boot environment for a ZFS root pool. The luactivate command is the preferred method of switching boot environments. For a UFS file system, you continue to use the OpenBoot^TM PROM OBP as the primary administrative interface, with boot options selected by using OBP commands.

• Starting with the Solaris 10 1/06 release for x86 based systems, a GRUB boot menu provides the interface for booting between different boot environments. Starting with the Solaris 10 10/08 release, this menu lists ZFS boot environments that are available for booting. If the default boot environment is a ZFS file system and the GRUB menu is displayed, you can let the default boot environment boot or choose another boot environment to boot. The GRUB menu is an alternative to using the luactivate command that is also used to boot a new boot environment for a ZFS root pool. The luactivate is the preferred method of switching boot environments.

On both SPARC and x86 based systems, each ZFS root pool has a dataset designated as the default root file system. If for SPARC, you type the boot command or for x86, you take the default from the GRUB menu, then this default root file system is booted.

If the GRUB menu has been explicitly modified to designate a default menu item other than the one set by Solaris Live Upgrade, then selecting that default menu entry might not result in the booting of the pool's default root file system.

For more information about booting and modifying the GRUB boot menu, see the following references.