[OpenAFS] RO v. RW path not behaving on setup

[Steven N. Hirsch]

On Sat, 28 Jun 2003, Derrick J Brashear wrote:

> On Sat, 28 Jun 2003, Steven N. Hirsch wrote:
> 
> > > > At this juncture, 'fs examine' should be showing the *.readonly volumes on
> > > > /afs and /afs/my_cell respectively.  Unfortunately, this does not happen.
> > > > I continue to see the rw volumes on both mount points - even after doing
> > > > fs checkvol.
> > >
> > > No it shouldn't. You mounted root.afs, not root.afs.readonly. You get
> > > root.afs.
> >
> > On p. 2-71 of the Transarc manual:
> >
> > ".. Verify that both volumes are now released.  First issue fs
> > checkvolumes to force the Cache Manager to notice that you have released
> > ReadOnly versions of the volumes, then issue fs examine again. This time
> > the output should mention root.afs.readonly and root.cell.readonly instead
> > of the ReadWrite versions, since the Cache Manager has a built-in bias to
> > access the ReadOnly version of root.afs if it exists."
> >
> > This is not how it works.  I continue to see the root.afs and root.cell
> > volumes until after an oops, shutdown and reboot cycle, at which point the
> > *.readonly volumes show up on those mount points!
> 
> For the Linux client, at least, what you see is as far as I know how it's
> always been.

Ok, I'll keep that in mind.

> 
> > > > everything _seems_ to look right!  Both /afs and /afs/my_cell show up as
> > > > being the *.readonly variants.  But, now I am unable to get proper RO/RW
> > > > pathing behavior.
> > >
> > > I've seen this bug but it went away when I switched to a newer kernel;
> > > What are you running?
> >
> > 2.4.21-pre2, which ran stable and flawlessly for months before I
> > accidently nuked the /vicepa partition.  Never had a shutdown problem.
> 
> Well, it only happens when you mount a RW root.afs and then replicate it,
> or at least that was the only time I could make it happen.

So, you do not recommend replicating root.afs then?  Given that I only 
have a single server, should _anything_ be replicated?

> > > That sounds like how it's supposed to work. /afs/my_cell is RO, you make
> > > an RO, you get an RO. You want writes, you do into /afs/.my_cell, or you
> > > donm't replicate the volume.
> >
> > Color me confused, then.  Previously, as a user I never needed to go into
> > the /afs/.my_cell explicitly to create/write a file.  Assuming that I have
> > the correct permissions, I would simply go to /afs/my_cell/blah, blah and
> > write.  Per the documentation, I assumed the cache manager was silently
> > accessing the rw volume in such cases.
> 
> Sure. *Your directory* isn't replicated, so the right thing happens.

I left out that step, but yes it was replicated.  Still, as mentioned in 
my earlier posting I was forced to explicitly point down the /afs/.my_cell 
hierarchy as a user.

> 
> > I thought the entire point of replication was to always read from an RO
> > volume, but force writes down the RW path?  Perhaps I'm either
> > misunderstanding you or am completely lost...
> 
> I think you're missing something.

Apparently.  I poked around on the Wiki, but couldn't find any links to an 
AFS installation guide other than the Transarc one.  Is there a good 
step-by-step writeup you can recommend?

Steve