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.
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