2.4.3 NFS
PowerHA works with the AIX network file system (NFS) to provide a highly
available NFS server, which allows the backup NFS server to recover the current
NFS activity should the primary NFS server fail. This feature is only available for
two-node clusters when using NFSv2/NFSv3, and more than two nodes when
using NFSv4, because PowerHA preserves locks for the NFS file systems and
handles the duplicate request cache correctly. The attached clients experience
the same hang if the NFS resource group is acquired by another node as they
would if the NFS server reboots.
When configuring NFS through PowerHA, you can control:
 The network that PowerHA will use for NFS mounting.
 NFS exports and mounts at the directory level.
 Export options for NFS exported directories and file systems. This information
is kept in /usr/es/sbin/cluster/etc/exports, which has the same format as
the AIX exports file - /etc/exports.
NFS and PowerHA restrictions
The following restrictions apply:
 Only two nodes are allowed in the cluster if the cluster is using
NFSv2/NFSv3. More than two nodes are allowed if using NFSv4.
 Shared volume groups that contain file systems that will be exported by NFS
must have the same major number on all nodes, or the client applications will
not recover on a fallover.
 If NFS exports are defined on the node through PowerHA, all NFS exports
must be controlled by PowerHA. AIX and PowerHA NFS exports cannot be
mixed.
 If a resource group has NFS exports defined, the field “file systems mounted
before IP configured” must be set to true.
 By default, a resource group that contains NFS exported file systems, will
automatically be cross-mounted. This also implies that each node in the
resource group will act as an NFS client, so must have a IP label on the same
subnet as the service IP label for the NFS server.
NFS cross-mounts
NFS cross-mounts work as follows:
 The node that is hosting the resource group mounts the file systems locally,
NFS exports them, and NFS mounts them. Thus becoming both an NFS
server and also an NFS client.
 All other participating nodes of the resource group simply NFS mount the file
systems, thus becoming NFS clients.
Chapter 2. High availability components 67
 If the resource group is acquired by another node, that node mounts the file
system locally and NFS exports them, thus becoming the new NFS server.
For example:
 Node1 with service IP label svc1 will locally mount /fs1and NFS exports it.
 Node2 will NFS mount svc1:/fs1 on /mntfs1.
 Node1 will also NFS mount svc1:/fs1 on /mntfs1.

Requirements for NFSv4
The cluster.es.nfs fileset that comes with the PowerHA installation medium
installs the NFSv4 support for PowerHA, along with a NFS Configuration
Assistant. To install this fileset, the following BOS NFS components must also be
installed on the system.
HACMP V5.4.x 6100-00 IZ02620 2.5.0.0
PowerHA V5.5 5300-09 2.4.10
PowerHA V5.5 6100-02-01 IZ31208 2.5.2.0
PowerHA/XD V5.5 5300-09 2.4.10
PowerHA/XD V5.5 6100-02-01 IZ31208 2.5.2.0
PowerHA/XD V5.5
GLVM Async
6100-02-03 IZ31208,IZ31205,
IZ31207
2.5.2.0
HACMP/PowerHA
Version
AIX OS Level Required APARs Minimum
RSCT Level
18 PowerHA for AIX Cookbook
For AIX Version 5.3:
 bos.net.nfs.server 5.3.7.0
 bos.net.nfs.client 5.3.7.0