3.5.1 Matrix Server Administration Guide

Chapter 8: Configure MxFS-Linux 136

the node. However, such access is not highly available because there is

no Virtual NFS Service associated with those connections. This is not a

security concern because the entire cluster should be considered as a

single security domain (for this and other reasons). The administrator

can track which nodes are exporting highly available NFS services by

watching the Export Group high-availability monitors that are active

on those nodes.

Mount PSFS Filesystems

Before configuring Export Groups, ensure that the filesystems to be

exported are on PSFS filesystems and are mounted on all the pertinent

nodes with the “persist” mount option.

The Cluster Coherent Record Locks mount option should not be disabled

on filesystems that will be exported. (Setting the command-line

localbrlocks mount option also disables cluster-coherent record locks.)

NFS lock acquisitions will not work on filesystems mounted with cluster-

coherent record locks disabled.

See “Configure PSFS Filesystems” on page 93 for details about creating

and mounting PSFS filesystems.

Considerations for Ensuring Data Safety

NFS write performance and the risk of data loss during NFS write

operations are affected by the use of the “sync” and “async” options. In

your configuration, you will need to determine whether the following

should be synchronous or asynchronous:

• The PSFS filesystem mount

• The server export of the PSFS filesystem

• The client mount of the exported data

For the least risk of data loss during NFS operations, use the “sync”

option for all of these components. Keep in mind however, that when

“sync” is used, NFS performance can be slow because each write must be

committed. As an alternative, you may prefer to use the “sync” option

only for server exports.