[OpenAFS] Swap RW and RO volumes ?

Derrick Brashear shadow@gmail.com
Wed, 16 Dec 2009 15:34:33 -0500

On Wed, Dec 16, 2009 at 3:19 PM, Richard Brittain
<Richard.Brittain@dartmouth.edu> wrote:
> We have some large data volumes not backed up in any way other than a dai=
> replicate to a different server. =A0The users normally access the volume =
> an explicit RW mount point.
> My question is, if I want to drain a volume of all RW volumes so I can do
> kernel updates etc. without a user-visible outage, is there any way to
> effectively swap the RW and RO volumes.
> Something like:
> =A0Lock RW
> =A0Release to bring RO in sync
> =A0Make RW 'offline'
> =A0Promote RO to RW in the VLDB
> =A0Demote old RW to RO in the VLDB
> =A0Unlock

I could imagine a tool which took the volume offline, rewrote the
volume header, changed the VLDB entry to invert the IDs, and put it
back online. There's no such tool that I know of now.

However, once they're in sync, you might be able to vos clone the
readonly on the non-rw site to an rw, then update the vldb. i'd have
to read code/try it.