On Wed, 16 Dec 2009 15:34:33 -0500 Derrick Brashear <[email protected]> wrote:
> On Wed, Dec 16, 2009 at 3:19 PM, Richard Brittain > <[email protected]> wrote: > > 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. So, do you need them to actually be normal RO volumes? This sounds more like a use case for shadow volumes, but you need to be a little careful with those. > > 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 > > Unlock You can sorta do part of that with 'vos convertROtoRW', but it's not a VLDB-only operation; you gotta change disk metadata, too. Can't convert an RW back to an RO, though. > 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. And I think there'd be problems if you tried to use such a thing with more than one RO. > 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. I thought something about the way we COW made cloning a bit one-way. At the very least, the vol header would indicate the clone as a non-RW, I think. -- Andrew Deason [email protected] _______________________________________________ OpenAFS-info mailing list [email protected] https://lists.openafs.org/mailman/listinfo/openafs-info
