As above /etc is what you need, but if you have SnapMirror licensed then I would use that to mirror your vol0 to another location. In a disk loss scenario, a Snapshot alone is not going to help you.
You can also use the config command (check the man page for it) to create a backup of the most important stuff, which you can store then somewhere else. At my old company, I used NDMP backups via CommVault to backup all of vol0 to tape. Also, its not just the config files you want, you may need logs and core dumps for troubleshooting as well. So again, best solution is mirror the whole root volume.
All good advice. I use snapshots, mirror, Ndmpcopy and config dump. Multiple methods and all covered by you guys.
Config dump does miss some settings like igroups and Lun mappings. Also has some issues with local groups and assigning no group to local users on config restore. With -v it is useful to get cifs shares. having multiple types of backups is good and config restore can be a big time saver. And having a mirror is always good to restore or mark as root.