In message <20051209114314.191073D87@string1.ciencias.uniovi.es>, Igor Sobrado 
writes:
>Hello!
>
>Is there a miniroot filesystem for NetBSD/i386?  From a search on
>google I see that some ports (e.g., sgimips) have a miniroot filesystem
>(diskimage.gz) that can be dumped to a small 32 MB filesystem.  I think
>that a miniroot filesystem would be nice; of course, NetBSD/i386 can
>be booted from a CD-ROM to a miniroot-like environment but a miniroot
>filesystem would be faster.
>
>I suppose that it is mostly a waste of space (I never had a serious
>problem with NetBSD), but a miniroot filesystem would be great to do
>some maintanance tasks or OS upgrades.   As it is mostly quiet, it
>should remain stable even in the case of a filesystem corruption that
>could damage the root filesystem.
>

Look at the archives of tech-embed for some discussions.  Also note the 
existence of /rescue on NetBSD.

		--Steven M. Bellovin, http://www.cs.columbia.edu/~smb