[OpenAFS] Swap RW and RO volumes ?

Richard Brittain Richard.Brittain@dartmouth.edu
Wed, 16 Dec 2009 15:19:12 -0500 (EST)

We have some large data volumes not backed up in any way other than a 
daily replicate to a different server.  The users normally access the 
volume via 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:
  Lock RW
  Release to bring RO in sync
  Make RW 'offline'
  Promote RO to RW in the VLDB
  Demote old RW to RO in the VLDB

Given that the incremental releases are usually quite small, the volume 
would be frozen for a short period only from the users point of view, and 
I'd have a server I could reboot without moving a lot of data around.

Has anyone thought about this ?

Richard Brittain,  Research Computing Group,
                    Kiewit Computing Services, 6224 Baker/Berry Library
                    Dartmouth College, Hanover NH 03755
Richard.Brittain@dartmouth.edu 6-2085