I'd like to be able to back up some of my machines to a holding disk at
arbitrary times.

For example, I run backups every night at 0100. Some laptop users are
unable to leave their machines overnight. I'd like to be able to start a
backup for their laptop(s) only, with the results going to the holding
disk for that nights 'real' backup.

Does anyone have some guidance for doing this? I assume that I'd need a
separate configuration file...

Thanks
-- 
Bob Tilden, tilden AT northwestern DOT edu
High Energy Physics Group
Northwestern University