Subject: Re: loopback filesystem
To: None <joe@mediaone.net>
From: Bill Studenmund <skippy@macro.Stanford.EDU>
List: current-users
Date: 03/29/1999 10:20:10
On Sat, 27 Mar 1999, Joseph Sarkes wrote:

> Andrew Gillham writes:
> > 
> > Read about 'vnd', or 'vnconfig', and you'll find it.
> > 
> > # vnconfig /dev/vnd0d myimage
> > # mount -t whatever /dev/vnd0d /mnt
> > etc..
> 
> yep, that works fine, thanks. One thing that confuses me is
> that running current, i don't end up with a vnd0d partition,
> just vnd0a, vnd0b, and vnd0c. Is the vnd0d thing from an 
> earlier version of NetBSD? The same thing shows up with cdroms
> for me. There is a man page that speaks about cd0d or something
> and I need to use cd0c or a as I recall.

What port are you running? On i386, for historical reasons, partition 'd'
is the whole-disk partition, whereas on (almost?) all other ports,
partition 'c' is the whole-disk partition.

> One thing that messed me up is that the whole "loopback" or 
> vnode setup is handled in linux by the mount command with
> a -o loop=/dev/loop3 or whatever in the mount command line.
> This appears to be a good thing to me, in that it allows you
> to put entries in the /etc/fstab file, which would not be
> possible under the NetBSD system unless one made entries in
> an rc file. Possibly of limited utility, but testing out
> a cdrom image is what I was looking to do, and the multiple
> steps is annoying, although not insurmountable... Yes, I AM
> a lazy sort of person...

The difference is that vnconfig is not a loopback filesystem, but a
loopback disk (to butcher terminology). It configures a files as a virtual
disk. The difference is that you can then partition this disk, and do a
whole lot more than just look at a filesystem. :-)

Take care,

Bill