Is it the OpenSolaris 2008.05 you upgraded ? In such case have you followed this post: http://www.opensolaris.org/jive/thread.jspa?threadID=62982&tstart=0 In particular see this: "PAY ATTENTION TO THE ATTACHED UPDATE PROCEDURE!!! Failure to do so will prevent your system from rebooting." ... "First, mount the clone under the /mnt directory
$ pfexec mount -F zfs rpool/ROOT/opensolaris-1 /mnt Next, update the GRUB configuration on your ZFS boot device(s) using $ pfexec /mnt/boot/solaris/bin/update_grub -R /mnt When you're ready to boot into the updated boot environment, you can reboot(1M) or init(1M) as usual." This message posted from opensolaris.org
