saving and restoring system images

[Boudreau]

Posted for a friend:

Has anyone ever worked with /etc/memsize before?

Two system scripts use the above, /etc/dumpsave /etc/ldsysdump.
I'm having trouble loading an image from diskette because
memsize results in a 0 on stdout when given /dev/rdsk/f0t on
it's command line. How does memsize work? Is there any neat trick
I could use to restore the image by some other means? I've tried
dd'ing it from disk but no good, crash won't recognise the image.

I using an interactive version of UNIX.

Thanks
Alan