Subject: Re: major hier(7) overhauls?
To: NetBSD Userlevel Technical Discussion List <>
From: Greg A. Woods <>
List: tech-userlevel
Date: 01/27/1999 15:25:55
[ On Wed, January 27, 1999 at 13:08:42 (-0500), Jim Wise wrote: ]
> Subject: Re: major hier(7) overhauls?
> Sure.  And taking away the division into / and /usr makes this
> customization a hell of a lot harder.

Not in my experience.  Customizing Unix for a truely small system has
always required a certain amount of hacking.  For example the "base"
system requires at least ~60MB on an i386 (with 1.3.3) unless you
manually strip stuff out, and that doesn't leave *any* breathing room
for swap or /var.  Sure you can use the separation of /usr to do some of
this thinking for you, in which case you'll need only a 20MB drive to
get an i386 system booted, but there are other ways around this without
requiring too much extra knowledge of system interdependencies.

Having a reliable and usable "union" filesystem would make things more
flexible, of course, but a working unionfs only gets around the issue of
having to give up your local disk for anything but swap or /var.  One
can always mount a full "root" filesystem over top of / from the network
server.  If you're really trying to boot systems with only 20MB disks
and share /usr from the network I think you'll find, as I did with my
38MB drive on a sun3, that re-mounting / from the network speeds things
up significantly -- some of those old disks can really drag a system to
their knees (though they are faster to boot from than an old floppy).

Like I said, I've done all of this (or its moral equivalent), and not
just with NetBSD, but with various Unix variants.  Like I also said,
this is an academic discussion -- not a proposal.  Further it's not even
an original idea on my part -- I'm only borrowing it from Plan 9 and
other not-quite-unix systems.  I just want to get people to think about
these kinds of things with an open mind because they raise all kinds of
interesting issues.

							Greg A. Woods

+1 416 218-0098      VE3TCP      <>      <robohack!woods>
Planix, Inc. <>; Secrets of the Weird <>