W3C Push Workshop, 8-9 September 1997

[Other Papers] [Briefing Package]

Title:    An NFS Replication Hierarchy

Speaker:  Brent Callaghan, Sun Microsystems


NFS is well known as the lingua franca of file access protocols.
It is installed, or is available for almost every computing
platform.  It is well known for its good performance, reliability
in the face of network and server outages, and its scalability
on large multiprocessor servers.

While NFS is commonly used by small LAN-based workgroups to share
data on a central server, it is now being used on wide area networks
and even on the Internet to provide file access for a much larger
audience.  NFS version 3 implementations can transfer large blocks
of data over TCP connections and new procedures like "readdirplus"
can be used to obtain directory information efficiently and WebNFS
clients can connect directly to a server through a packet filter
firewall or application proxy like SOCKS.

NFS clients can be configured to switch automatically from one
NFS replica server to another.  There is nothing special required
of an NFS replica server other than the replica filesystems
being consistent.

An NFS replication hierarchy is a hierarchical configuration of
NFS clients and servers that maintain replicated filesystems.
Each member of the hierarchy accepts changes to its replica
from a server higher in the tree and may accept changes for
several replica filesystems each with its own source server.

The presentation will show how the NFS protocol can make efficient
use of network bandwidth in delivering changes down a hierarchy
with provision for fault tolerance and recovery.  A replication
hierarchy can be implemented with existing NFS clients and servers.