White Paper

1. Abstract

This white paper describes how the Serviceguard NFS Toolkit supports the Veritas

Storage Foundation Cluster File System (VxCFS, referred to as CFS throughout this

document) in a Highly Available NFS environment. In a Serviceguard NFS Toolkit

implementation with VxFS file systems (i.e. a non-CFS implementation), access from

NFS clients to specific files and file systems in a Serviceguard NFS environment is

limited to a single NFS server node. By configuring Serviceguard NFS Toolkit to utilize

CFS, simultaneous access to files and file systems from multiple NFS server nodes is

now possible. This paper describes how to configure Serviceguard NFS Toolkit to work

with CFS and compares the CFS and non-CFS implementations. This document can be

considered an addendum to the Serviceguard NFS Toolkit Administrator’s Guide.

2. Intended Audience

This white paper is intended for administrators who configure the Serviceguard NFS

Toolkit.

3. Introduction

Non-CFS Implementation with Package Failover

Serviceguard NFS Toolkit allows you to use Serviceguard to set up highly available

NFS servers. An NFS server is a host that shares its local directories (i.e. makes

them available for client hosts to mount using NFS). On the NFS client, these

mounted directories look to users like part of the client’s local filesystem. With

Serviceguard NFS, the NFS server package (also referred to as an NFS failover

package) containing the exported filesystems can move to a different node in the

cluster in the event of failure. After Serviceguard starts the NFS package on the

adoptive node, the NFS filesystems are re-exported from the adoptive node with

minimum disruption of service to users. The client system hangs until the NFS

server package comes up on the adoptive node. When the service returns, the

application can continue access to the file. You do not need to restart the client

system or the client applications accessing the NFS filesystem. This implementation

will be referred to throughout this document as a non-CFS implementation. Non-

CFS implementations mostly use VxFS filesystems, so the term VxFS will also be

used to refer to the non-CFS implementation.

Integrating Support for CFS into Serviceguard NFS Toolkit

In a non-CFS implementation, access to a specific file must go through a single NFS

server which can limit scalability and cause a performance bottleneck. With CFS,

files and filesystems may be accessed concurrently from multiple servers. By

integrating CFS into a Serviceguard NFS environment, files and filesystems can be

accessed concurrently from multiple highly available NFS servers to improve

performance, scalability, and availability.

Initial Serviceguard NFS Toolkit support for CFS will be limited in scope, specifically

for applications that require file locking across NFS mounts during a failover. For

applications that do not require file locking during a failover, a DNS round-robin

scheme or other load balancing tools may be used to distribute the load evenly

between the servers. Additional support will be phased into future releases.