Why are NFSv4 callbacks not setup correctly in a High Available NFS-server environment?

Solution Verified - Updated -

Issue

In a clustered NFS environment, the NFSv4 callbacks are not setup correctly.

The NFS-client mounts an export on a fake NFS-server, the 'loadbalancer or director' in the diagram. This fake NFS-server forwards the connection on to one of the real NFS-servers.

                 +------------+
                 | NFS-client |
                 +------------+
                        | 192.168.130.24
                        |
                        |
                        | 192.168.130.23
                +--------------+
                | loadbalancer |
                |      or      |
                |   director   |
                +--------------+
                        |
                        |
         +--------------+-------------+
         |                            |
         | 192.168.130.20             | 192.168.130.21
+--------+--------+          +--------+--------+
| real NFS-server |          | real NFS-server |
+-----------------+          +-----------------+

Now, when one of the read NFS-servers tries to setup the callback path to the NFS-client, the IP-address from the originating NFS-server is not the same as the one which the NFS-client used to mount the export. It seems that the NFS-client does not accept the CB_NULL procedure call from the real NFS-servers, as the NFS-client does not send a reply on the procedure call.

Environment

  • Red Hat Enterprise Linux 5, 6.0 and 6.1
  • mounting NFS exports over NFSv4 from a clustered NFS server

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