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:
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