3.1.2 MxFS-Linux Administration Guide

Chapter 2: Configure Export Groups 8

Service; they do not need to know which physical node is providing the

service. Clients can access any of the filesystems specified in the Export

Group by using the DNS name or IP address of the Virtual NFS Service.

When you create a Virtual NFS Service, you will need to assign it to a

primary node and one or more backup nodes. A Virtual NFS Service can

be associated with only one Export Group. However, you can assign the

same Export Group to multiple Virtual NFS Services.

One or Many Export Groups?

In the typical configuration, a single Export Group associated with

multiple Virtual NFS Services is recommended.

High Availability and Failover Support

MxFS provides high availability for the exported PSFS filesystems. To

ensure that the filesystems are always available, MxFS provides a

high-availability monitor for each Export Group. On each server

configured for the Export Group, this monitor periodically checks the

exported filesystems and the NFS daemon to determine whether they can

be accessed externally.

If the server to which NFS clients are connected should fail or lose access

to the PSFS filesystem (for example, because of a SAN problem), the

monitor probe will report the failure. The Virtual NFS Services using that

server as their primary are then failed over (redirected) to a backup

server. Failover is transparent to the NFS clients; their access to the

exported filesystems continues after a brief pause.

Caveats Regarding Export Groups

Before creating an Export Group, you should be aware of the following:

• Although you can configure multiple Export Group files, with each

group having its own set of export records, all of the export records

are ultimately merged into a single /etc/exports file that is

automatically installed on each node in the cluster. Because an export

can be included in more than one Export Group, the /etc/exports file

can contain multiple records referring to the same filesystem path to

be exported. If these duplicate records specify different export