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

Jeffrey Altman jaltman@your-file-system.com
Mon, 13 May 2013 13:47:52 -0400


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On 5/13/2013 1:34 PM, Andrew Deason wrote:
> On Fri, 10 May 2013 13:05:34 +0200
> Christof Hanke <christof.hanke@rzg.mpg.de> wrote:
>=20
>> 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.
>=20
> 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:
>=20
>  - 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,
>    etc)
>=20
> 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 R=
O
> copies, you must use the RO. From a user perspective, it just seems lik=
e
> such a weirdly specific restriction.
>=20
> 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 sill=
y
> 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.

I have no objection to a change to explicitly mount the rw instance of a
volume as /afs.  That is not what was proposed in the patch to gerrit.
The patch to gerrit modifies the volume selection semantics for all volum=
es.

I would also have no objection to a patch that permits dynroot to
explicitly mount the rw instance of root.cell provided that the behavior
can be specified on a per mount basis.

Jeffrey Altman



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