If I concocted a JFdriver that allowed ONE unit only, and subset
functions (i.e., no controls except what disk gets frag-avoided,
preset limits on sizes used) it might fill the bill, but I'm
worried that some folks might be able to patch the driver image
and fake around. If the jfctl image had "jfa0:" hardwired in it,
of course, that'd make such driver patching hard to use.

Then a demo could be there of this sort along with a full kit.
By using the same drivername with the demo as the full kit,
you'd have to load either the cut-down JFdriver or the real one,
not both, and if you started using the real kit it might be
unpleasant to go to the limited one again.

I would have to ensure too that a cut-down jfctl image tested
that the fake driver was in use. I can do that easily by having
a different "magic number" in its UCB which I use to ensure
that it really IS JFdriver. That way, no matter what people
tried, they couldn't do frag avoidance with the real multiunit
driver by assigning jfa2: to jfa0:, say, before running the
control image.

Actually, the PRODUCT could be modified a bit if we wanted. I could
fix it pretty easily so that the control image would allow real
frag avoidance on JFA0: regardless (since ucb$w_unit is available
and can't be faked) of license, but all nonzero units would need
the license or they wouldn't work.

Other forms of demo-mode operation are possible, such as testing
for host device name. Allow VDA0: or DCA0: using my vddriver to
be frag avoided free, but nothing else, for example.

I guess I might favor saying you'd need a license to fragavoid more
than one disk or to control any optional parameters even on that
one disk. Perhaps also try to say that for free you can't use it on
your system disk (to ensure that one-disk sites can't totally
get it free)...sys$sysdevice UCB is obtainable fairly reasonably
and would do. The package runs fine on a system disk - I've used it
on mine for months - but I don't want to lose all access to that
part of the market whose disk is ONE (possibly large) system disk
just because they can get it free otherwise. After all, you can
get 10GB on one drive these days. Someone with one physical drive
can still fragavoid one virtual disk. (Maybe FA should be
packaged with virtual disks...)