Issues using unionfs and vnode backed disks

David Schultz das at FreeBSD.ORG
Sun May 2 17:26:11 PDT 2004

On Mon, May 03, 2004, Jacques Marnweck wrote:
> Basically how I do jail()'ed virtual machines is that I first create a
> base disk image say which all the jails get so I only have to maintain
> one base installation which can be shared amongst multiple jails.
> Another bug I noticed which had similar side effects was where I had /usr/ports
> mounted below /home/jails/base/usr/ports and from the jail()'ed virtual
> machine I typed 'make install clean' to install a port, the box had a
> deadlock.

I seem to recall that there are known issues with unionfs on
memory-backed devices.  See also PR kern/54534.

> >From reading various posts here, I'm assuming that unionfs under FreeBSD
> 5.2.1-RELEASE-p5 should have less issues, and should not cause the
> problems I'm experiencing?
> Also I've tested this a couple of times today.  Who is maintaining the
> unionfs code, as I would like to chat to him/her.

I'm not sure what gave you that impression; unionfs has always
been an unsupported use-at-your-own-risk feature *precisely*
because it doesn't have a maintainer.  (See the mount_unionfs(8)
manpage.)  Occasionally people fix problems with it, but it isn't
held to the same standards as the rest of the system because
nobody has the necessary combination of time, interest, and
ability to work on it.  You're welcome to report problems, and
that's definitely beneficial when someone does have time to look
at it, but please check the PR database to make sure you're not
submitting a duplicate of an existing PR.

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