HP-UX 11i December 2004 Release Notes

Disk and File Management
Network File System Support on TCP/IP
Chapter 11
246
Network File System Support on TCP/IP
new at 11i
original release
With versions 2 and 3, Network File System (NFS) is now supported over the
connection-oriented protocol, TCP/IP, in addition to running over User Datagram
Protocol (UDP).
As a result of this new functionality, NFS is now supported over wide-area networks
(WANs). As long as TCP is supported on the WAN, then NFS is supported also. (TCP
transport increases dependability on WANs. Generally, packets are successfully
delivered more consistently because TCP provides congestion control and error recovery.)
The mount_nfs command now supports a proto= option on the command line where the
value for proto can be either UDP or TCP. (In the past, this option was ignored.) This
change allows administrators to specify which transport protocol they wish to use when
mounting a remote file system.
If the proto= option is not specified, then NFS, by default, will attempt a TCP
connection. If that fails, it will then try a UDP connection. Thus, by default, you will
begin using TCP instead of UDP for NFS traffic when you begin using the 11i version of
HP-UX. This should have little impact you. You do, however, have the option to specify
either UDP or TCP connections.
If you specify a proto= option, only the specified protocol will be attempted. If the server
does not support the specified protocol, the mount will fail.
The nfsd daemon now opens TCP transport endpoints to receive incoming TCP requests.
For TCP, nfsd is multi-threaded. For UDP, nfsd is still multi-processed.
Kernel TCP threads execute under the process nfskdtcp. When counting the number of
nfsd processes, keep in mind the following algorithm: An equal number of nfsds that
support UDP will be created per processor, but only one nfsd that supports TCP will be
created. In the case of a four-way machine and NUM_NFSDS=14 (set in
/etc/rc.config.d/nfsconf), 17 nfsds will be created: 16 for UDP (4 per processor) and
1 for TCP.
The nfsstat command now reports TCP RPC statistics for both client and server. The
TCP statistics are under the connection-oriented tag and the UDP statistics are under
the connectionless-oriented tag.
AutoFS supports the proto= option in the Automounter maps and has the same
behavior described above under the mount_nfs command. In the past, this was an
invalid option.
However, Automounter will not support NFS over TCP.
Unlike the 11.0 patch release of NFS over TCP, there is no enablement flag in the 11i
release for NFS over TCP. By default, NFS will attempt to use TCP.
The kernel RPC layer has been modified to support TCP connections over NFS. A new
streams module, rpcmod, has been added to manage the TCP connections. These changes
are internal to the NFS implementation and are not user accessible.
Documentation Changes
The following manpages have been modified for this new feature: