Peter Memishian has pointed out that the statement that /etc/path_to_inst is a "pure cache" is not correct. It is true that a functional instance file can be rebuilt but solaris does rely on the instance number ordering in the instance file not to change, otherwise devices could be renumbered. Additions to the instance file aren't necessary to boot, because the earlier version must have been bootable too. And since changes are cumulative, any additions in the updated file can be merged without needing manual intervention. Hence a discrepancy between the two instance files is not cause to invalidate the archive.
-jg
