From: Trond Myklebust Subject: Re: [autofs] Re: [NFS] Re: [RFC] Multiple server selection and replicated mount failover Date: Wed, 24 May 2006 14:31:41 -0400 Message-ID: <1148495501.11732.8.camel@lade.trondhjem.org> References: <1148488156.5872.42.camel@lade.trondhjem.org> Mime-Version: 1.0 Content-Type: text/plain Cc: Ian Kent , linux-fsdevel , autofs mailing list , nfs@lists.sourceforge.net Return-path: To: Jeff Moyer In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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 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