[OpenAFS] Re: Making the R/O preference when crossing mount points configurable

Andrew Deason adeason@sinenomine.net
Mon, 13 May 2013 12:34:49 -0500

On Fri, 10 May 2013 13:05:34 +0200
Christof Hanke <christof.hanke@rzg.mpg.de> wrote:

> As for your general problem,
> we've set up a special machine called "afsrw", where we mounted a
> special "root.cell.rw" volume, which has no RO-copies.
> Like this, we are always in the RW-Path on that machine and can
> perform the "make install" into the RO-PATH.

Yeah, this is one way to achieve this. From discussing with Arne, I
believe that that approach is undesirable because it requires an
administrator to create (and maintain) such a 'root.cell.rw' volume.
Having a separate startup option to afsd to just mount the root vol RW I
think has a few advantages:

 - It doesn't require anything from an administrator
 - It works/could work for -dynroot
 - It means you don't have to maintain two separate root volumes (if
   they ever change for whatever reason, or if you move them around,

It also just seems a bit silly to me that you can currently say that
/afs can point to any volume anywhere in AFS space, but if it has any RO
copies, you must use the RO. From a user perspective, it just seems like
such a weirdly specific restriction.

The only downside I am aware of is possible confusion that /afs points
somewhere else. But it seems much more clear to me than the current
practice of pointing -rootvol somewhere else. If someone uses some silly
name like '-rootvol root.afs2', it's not very clear what is being done
or why; since what it's doing depends on the contents of 'root.afs2'.
But if you have something like '-rwrootvol', that always means that we
want an RW /afs, regardless of cell/volume contents.

Andrew Deason