This chapter contains instructions for configuring Red Hat Enterprise Linux to make network file sharing services through NFS and Samba highly available.
A highly-available network file system (NFS) is one of the key strengths of the clustering infrastructure. Advantages of clustered NFS services include:
Ensures that NFS clients maintain uninterrupted access to key data in the event of server failure.
Facilitates planned maintenance by allowing transparent relocation of NFS services to one cluster member, allowing you to fix or upgrade the other cluster member.
Allows setup of an active-active configuration to maximize equipment utilization. Refer to Section 6.5 NFS Configuration: Active-Active Example for more information.
To create highly available NFS services, there are a few requirements which must be met by each cluster member. (Note: these requirements do not pertain to NFS client systems.) These requirements are as follows:
The NFS daemon must be running on all cluster servers. Check the status of the servers by running the following:
/sbin/service nfs status
NFS services will not start unless the following NFS daemons are running: nfsd, rpc.mountd, and rpc.statd. If the service is not running, start it with the following commands:
/sbin/service portmap start
/sbin/service nfs start
To make NFS start upon reboot and when changing runlevels, run the following command:
/sbin/chkconfig --level 345 nfs on
The RPC portmap daemon must also be enabled with the following command:
/sbin/chkconfig --level 345 portmap on
File system mounts and their associated exports for clustered NFS services should not be included in /etc/fstab or /etc/exports. Rather, for clustered NFS services, the parameters describing mounts and exports are entered via the Cluster Configuration Tool. For your convenience, the tool provides a Bulk Load NFS feature to import entries from an existing file into the cluster configuration file.
NFS cannot be configured to run over TCP with Red Hat Cluster Manager. For proper failover capabilities, NFS must run over the default UDP.
For detailed information about setting up an NFS server, refer to the Red Hat Enterprise Linux System Administration Guide.