tape backup on RS/6000

[Judy P. Halchin]

I am trying to backup an RS/6000 to 8mm tape, and I have two problems.  The
first (which I saw asked here a few weeks ago, but never saw an answer) is
how do I backup all my filesystems onto a single tape.  After backing up each
filesystem it rewinds the tape, forcing me to use a new one for the next
filesystem.  There must be a better way!  Second, it warns me that a backup
may not be any good if the filesystem was not unmounted first.  When I tried
to unmount /usr I got a message that it was busy.  I think this is surely 
because /usr/lib/sendmail and /usr/lib/errdemon were running.  sendmail poses
no problem, but the man page for errdemon tells me not to stop and restart it.
How then, am I to make a good backup of /usr?  What terrible things will 
happen if I stop and restart errdemon?

Any help will be greatly appreciated.

Judy Halchin
Eastern Illinois University
cfjph at ux1.cts.eiu.edu