Introducing Network File System Version 4 on HP-UX 11i v3

Abstract

Beginning with HP-UX 11i v3, HP offers Network File System Version 4 (NFSv4). NFSv4 offers better

interoperability with Microsoft® Windows®, improved security, and improved performance. This

paper describes the NFSv4 features available in the initial and subsequent fusion releases of HP-UX

11i v3 and what an HP-UX system administrator needs to know to use NFSv4 clients and servers.

New features of NFSv4

The new NFSv4 features offered in HP-UX 11i v3 are:

• NFSv4 introduces state. NFSv4 is a stateful protocol unlike NFSv2 or NFSv3.

• NFSv4 introduces file delegation. An NFSv4 server can enable an NFSv4 client to access and

modify a file in its cache without sending any network requests to the server.

• NFSv4 uses compound remote procedure calls (RPCs) to reduce network traffic. An NFSv4 client

can combine several traditional NFS operations (LOOKUP, OPEN, and READ) into a single

compound RPC request to carry out a complex operation in one network round trip.

• NFSv4 specifies a number of sophisticated security mechanisms including Kerberos 5 and Access

Control Lists.

• NFSv4 can seamlessly coexist with NFSv3 and NFSv2 clients and servers.

Note:

The HP-UX base file system supports only POSIX ACLs. So, the NFS server maps NFSv4 ACLs to POSIX ACLs.

This might result in loss of NFSv4 ACL granularity.

NFSv4 changes

Five big differences between the NFSv4 protocol and earlier Network File System (NFS) protocol

versions are:

• Compound RPCs (There are now only two RPCs, the NULL procedure, and the COMPOUND

procedure.)

• Elimination of a separate mount, locking, and ACL protocols

• Introduction of state into the protocol

• Security

• Delegation

COMPOUND remote procedure call

A common complaint of earlier NFS protocols was that the request-response nature of NFS was

inefficient. That is, if a request depended on the results of a previous request, then the client had to

wait for a reply from the server before sending the second request. Consequently, there was

unnecessary latency inherent in the protocol. COMPOUND requests provide a mechanism by which

clients can bundle multiple NFS operations into a single over-the-wire request.

In this paper, NFS requests and replies are displayed using Ethereal traces. Ethereal, also known as

Wireshark, is a multiprotocol network analyzer tool available from the HP Internet Express Bundle

(http://software.hp.com) or by free download from http://www.ethereal.com. Ethereal displays the

NFSv4 requests and replies as they are sent over the wire. Included in the output are all the fields

specified by the protocol. Because the output can be quite long, sections of the output have been

deleted and replaced with ellipsis.