Subject: Re: unionfs
To: Phil Knaack <firstname.lastname@example.org>
From: Bert Driehuis <email@example.com>
Date: 11/20/1996 00:57:47
> Someone mentioned that the problems with unionfs have to do with
>two simultaneous processes accessing a union-mounted area, although I've
>been using union-mounted source directories to rebuild the world for many
>moons and versions of netbsd, and have never seen a problem.
> Of course, on every machine I use unionfs on, I happen to be the
>only user who has an account. =-)
Hmmm, just today, I unpacked the 1.2 source tree (on my freshly upgraded
Sparc running the GENERIC 1.2 kernel) onto /usr/src, which is a null mount
over /home/_src, and while tar was chugging away creating stuff, I was
browsing /home/_src/sys/net (which by that time, tar was long done with).
When I tried file name completion on /home/_src/sys/net, both my shell and
tar hung in a deadlock (sorry, didn't write down the WCHAN, I was
programming in another window at the time and was thus mentally elsewhere).
So, at least nullfs in 1.2 still has a deadlock potential. I sometimes also
see console messages "null_node_find: vget failed". Those appear without
I haven't tried unionfs in 1.2 yet; I know that people have been fixing
some things, so it might be an idea to use unionfs instead. Haven't tried
Bert Driehuis God, grant me the serenity to accept the things
firstname.lastname@example.org I can't change, courage to change the things I
can, and the wisdom to know the difference.