You can easily set up a pool of NFS nodes with HA and failover using virtual IP addresses (VIPs); if one node fails the VIP will be automatically reassigned to the next NFS node in the pool. If you do not specify a list of NFS nodes, then MapR uses any available node running the MapR NFS service. You can add a server to the pool simply by starting the MapR NFS service on it. Before following this procedure, make sure you are running NFS on the servers to which you plan to assign VIPs. You should install NFS on at least three nodes. If all NFS nodes are connected to only one subnet, then adding another NFS server to the pool is as simple as starting NFS on that server; the MapR cluster automatically detects it and adds it to the pool.
You can restrict VIP assignment to specific NFS nodes or MAC addresses by adding them to the NFS pool list manually. VIPs are not assigned to any nodes that are not on the list, regardless of whether they are running NFS. If the cluster's NFS nodes have multiple network interface cards (NICs) connected to different subnets, you should restrict VIP assignment to the NICs that are on the correct subnet: for each NFS server, choose whichever MAC address is on the subnet from which the cluster will be NFS-mounted, then add it to the list. If you add a VIP that is not accessible on the subnet, then failover will not work. You can only set up VIPs for failover between network interfaces that are in the same subnet. In large clusters with multiple subnets, you can set up multiple groups of VIPs to provide NFS failover for the different subnets.
You can set up VIPs with the virtualip add command, or using the Add Virtual IPs dialog in the MapR Control System. The Add Virtual IPs dialog lets you specify a range of virtual IP addresses and assign them to the pool of servers that are running the NFS service. The available servers are displayed in the left pane in the lower half of the dialog. Servers that have been added to the NFS VIP pool are displayed in the right pane in the lower half of the dialog.