Re: [autofs] Re: [NFS] Re: [RFC] Multiple server selection and replicated mount failover

[Trond Myklebust <trond.myklebust@fys.uio.no>]

On Wed, 2006-05-24 at 13:58 -0400, Jeff Moyer wrote:
> ==> Regarding [autofs] Re: [NFS] Re: [RFC] Multiple server selection and replicated mount failover; Trond Myklebust <trond.myklebust@fys.uio.no> adds:
> 
> trond.myklebust> On Wed, 2006-05-24 at 13:05 +0800, Ian Kent wrote:
> >> > 4) How does NFS v4 fit into this picture as I believe that some
> >> >    of this functionality is included within the protocol.
> >> 
> >> And this.
> >> 
> >> NFS v4 appears quite different so should I be considering this for v2 and 
> >> v3 only?
> 
> trond.myklebust> NFSv4 has full support for migration/replication in the
> trond.myklebust> protocol. If a filesystem fails on a given server, then
> trond.myklebust> the server itself will tell the client where it can find
> trond.myklebust> the replicas. There should be no need to provide that
> trond.myklebust> information at mount time.
> 
> And what happens when the server disappears?

There are 2 strategies for dealing with that:

Firstly, we can maintain a cache of the list of replica volumes (we can
request the list of replicas when we mount the original volume).

Secondly, there are plans to add a backup list of failover servers in a
specialised DNS record. This strategy could be made to work for NFSv2/v3
too.

Cheers,
  Trond