3.1.2 MxFS-Linux Administration Guide

Chapter 2: Configure Export Groups 10

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.

The “async” option provides better NFS write performance, as it allows

writes to be acknowledged before being committed on disk; however, it

gives less coherency with regard to on-disk contents in the cluster.

Consequently, server crashes can lead to silent-data-loss; the NFS client

may never be aware of a given server crashing because MxFS provides for

seamless fail-over.