Highly Available NFS® is a tool kit that
allows you to use MC/ServiceGuard to set up highly available NFS
servers.
You must set up an MC/ServiceGuard cluster before you can
set up Highly Available NFS. For instructions on setting up an MC/ServiceGuard
cluster, see the Managing MC/ServiceGuard
manual.
Highly Available NFS is a separately purchased set of configuration
files and control scripts, which you customize for your specific
needs. These files, once installed, are located in /opt/cmcluster/nfs.
MC/ServiceGuard allows you to create high availability clusters
of HP 9000 Series 800 computers. A high availability computer system
allows applications to continue in spite of a hardware or software
failure. Highly available systems protect users from software failures
as well as from failure of a system processing unit (SPU) or local
area network (LAN) component. In the event that one component fails,
the redundant component takes over, and MC/ServiceGuard coordinates
the transfer between components.
An NFS server is a host that "exports" its
local directories (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 file system.
With highly available NFS, the NFS server package containing
the exported file systems can move to a different node in the cluster
in the event of failure. After MC/ServiceGuard starts the NFS package
on the adoptive node, the NFS file systems are re-exported from
the adoptive node with minimum disruption of service to users. The
client side "hangs" until the NFS server package
comes up on the adoptive node. When the service returns, the user
can continue access to the file. You do not need to restart the
client.
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