Re: round robin dns, multihomed host, nfs mounting issues

["Davis, Jeff (Houston)" <jdavis@hess.com>]

Given Neil's comments about possible glibc bug and nfs 1.05, and my =
sense that it is working, is it reasonable for me to think its working?

I.e should it work?

Thx...jeff


--------------------------
Jeff Davis
Amerada Hess
Global IT Infrastructure
Technical Computing
Houston, Texas
jdavis@hess.com
713-609-5436 (work)
281-467-9448 (cell)

Sent by BlackBerry Wireless Email

-----Original Message-----
From: Neil Brown <neilb@cse.unsw.edu.au>
To: Davis, Jeff (Houston) <jdavis@hess.com>
CC: nfs@lists.sourceforge.net <nfs@lists.sourceforge.net>
Sent: Sat Jul 19 05:34:21 2003
Subject: Re: [NFS] round robin dns, multihomed host, nfs mounting issues

On  July 18, jdavis@hess.com wrote:
> I'm testing out a NFS server which has two interfaces on two different
> subnets. I'm using a single hostname and round robin dns. Clients are
> both RedHat Linux systems.
>=20
> I can access the primary interface on server via NFS from any system =
on
> my network. I can only access the second interface from hosts on the
> same subnet. Unfortunately, round robin dns on systems that are not
> local to subnets on either of the server's nics will randomly get one =
of
> the two nics to access nfs fs through.=20
>=20
> int 1 - 192.168.19.224
> int 2 - 172.25.2.106
>=20
> # can mount through int 1 from any host\
> # can mount thoughh int 2 from same ip subnet as int 2
> # cannot mount throught int 2 from remote ip subnets
> # on local subnets, mounts work as desired through correct, optimal
> interface on nfs server
>=20
> # on remote subnets, round robin directs ~50% of mount requests
> to server through int 2 which fail
>=20
> why doesn't this work?

Looks like you've hit a glibc bug that was only fixed relatively
recently (27th Feb 2003.  glibc version 2.3.2 or 2.3.3 I think).

When mountd is sending it's reply, it uses sendmsg and insists that the
reply goes out the same interface that the request came in on.  If
that interface doesn't have a route to the client, you lose.

I worked around it by putting a default route on all my interfaces.

> upgrading to nfs-utils 1.05 seems to have helped

I doubt that it really did, but if it works now, great.

NeilBrown



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