using fss snapshots

[Brook Milligan <brook%biology.nmsu.edu@localhost>]

I am trying to create ffs snapshots with fssconfig.  Following [1], I can create a snapshot with

	# fssconfig -cx fss0 / /tmp/back

However, following fssconfig(8), the command

	# fssconfig fss0 /usr /tmp/back

yields the following error:

	fssconfig: /dev/rfss0: FSSIOCSET: Invalid argument

So far, anything with the path argument not / yields the invalid argument.

Clearly, I must be doing something wrong, but cannot figure out what that would be.  This is all 11.0/amd64.  

Suggestions welcome.  Thanks a lot.

Cheers,
Brook

[1] https://wiki.netbsd.org/tutorials/the_netbsd_system_manager__39__s_manual/#index34h2