From: trmcneal@comcast.net
Subject: Re: An NFS-HA HOWTO anyone? WAS> Re: Stopping NFS, ip address take over, zero-copy NFS for 2.4.21, and misc
Date: Mon, 22 Sep 2003 16:33:51 +0000
Sender: nfs-admin@lists.sourceforge.net
Message-ID: <E1A1Tdp-0003nc-9S@sc8-sf-mx1.sourceforge.net>
To: nfs@lists.sourceforge.net
Errors-To: nfs-admin@lists.sourceforge.net

Hi -

The NFS failover is not that simple, depending on the HA cluster used.
Mission Critical Linux used an IP migration scheme, but had to jump through
hoops to force the client to renegotiate; otherwise the new server would just
look at the file handle, which had MAC address info, and return errors.
They (ok, We) did not publish that in open source, so that the Convolo 
cluster had lock failover capability, but the open source Kimberlite cluster
did not.

Anyway, since the behavior is so product dependent, it hasn't been really
addressed in the FAQ, but I'll look at it again.

Regards -

Tom

--
Tom McNeal
(650)906-0761(cell)
(650)964-8459(fax)
> On Sat, 2003-09-20 at 05:22, ian sison (mailing list) wrote:
> > 
> > On Fri, 19 Sep 2003 rnews@tasking.nl wrote:
> > 
> > > Chris Worley <cworley@lnxi.com> wrote:
> > > | 2) IP address takeover between NFS servers.
> > > |
> > > | With NFS stateless, and not running lock servers, I thought a simple IP
> > > | address takeover scheme (when an I/O server goes down, another just adds
> > > | the failed server's IP address as a virtual interface) would allow
> > > | clients to immediately renegotiate with the same IP address pointing to
> > > | another NFS server (serving the same partitions).  The take-over is
> > > | successful: the clients can communicate with the new I/O server, but I
> > > | get "permission denied" (as root or otherwise) on the NFS mounted
> > > | partitions most of the time (sometimes it works).
> > >
> > > You need to migrate the entries in /var/lib/nfs/rmtab to the new
> > > machine. Also, when the device number on the new machine differs
> > > from the device number on the old machine, you need to use the "fsid"
> > > option in /etc/exports, to make sure the file handles don't change.
> > 
> > This is important information, and it should go into a howto. NFS-HA is a
> > very common requirement nowadays, and there's very little information i've
> > seen on the net except for the Mission Critical Linux site.
> > 
> I need to update info on the page, and quite honestly, i think the info
> i have is buggy.. (I will update this week), but i have a document
> showing how I achieve 'Active-Active' HA NFS over Shared SCSI.. Mainly,
> it's by replicating rmtab entries by storing mountpoint specific rmtab
> entries on the shared storage mountpoint... 
> 
> the address is:
> 
> http://chilli.linuxmds.com/~mschilli/NFS/
> 
> Bookmark the page, and I promise by mid week, i'll have it updated.. I
> will post to the mailing list when the update is complete.
> 
> Matt Schillinger
> mschilli@vss.fsi.com
> > 
> > 
> > 
> > 
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