NFS cross-mounting in PowerHA SystemMirror
An NFS cross-mounting is a specific PowerHA® SystemMirror® NFS configuration where each node in the cluster can act as both the NFS server and the NFS client. While a file system is being exported from one node, the file system is mounted with NFS on all the nodes for the resource group, including the one that is exporting it. Another file system can also be exported from another node, and be mounted with NFS on all nodes.
When your environment uses NFS version 2 and version 3 to export in resource groups, the cross-mount capability is restricted to only two node resource groups. If the resource group contains only NFS version 4 (or later) exports, the cross-mount capability is extended up to any number of nodes that are supporting a resource group.
Each node in the resource group is part of a mutual takeover (or active-active) cluster configuration, providing and mounting an NFS file system.
By default, resource groups that contain exported NFS file systems automatically cross-mount these file systems (if both export and import are configured) as follows:
- On the node currently hosting the resource group, all NFS file systems in the group are NFS exported.
- Each node that might host this resource group NFS mounts all the NFS file systems in the resource group.
Applications access the NFS file systems on any node that is part of the resource group.
When a fallover occurs for a resource group that is configured with IP address takeover, the NFS file system is locally mounted by the takeover node and re-exported. All other nodes in the resource group maintain their NFS file system mount.
claddres: WARNING: NFS mounts were specified for the resource group
'<RG name>';however no NFS exports have been specified.