Tuning networking resources

NFS resources

The Network File System (NFS) software allows one computer (an NFS client) attached to a network to access the filesystems present on the hard disk of another computer (an NFS server) on the network. An NFS client can mount the whole or part of a remote filesystem. It can then access the files in this filesystem almost as if they were present on a local hard disk.

The speed of access to data is designed to approach that achievable using the server's hard disk directly. The performance of NFS is limited by:

The maximum throughput of the underlying network technology. For example, Ethernet is capable of transferring up to approximately 1.25MB/s.
The performance of the server's hardware subsystems including network adapters, and hard disks. Network adapters on an NFS server should have high specifications. They should at least have a 16KB I/O buffer and 32-bit data path, and, if possible, they should be capable of performing Bus Master DMA.
The configuration of the buffer cache, STREAMS, and TCP/IP on the server.
The number of daemons running on the server to service requests from network clients.
The loading of the network which determines the effective throughput to and from the client.
Demands for network file access to the server from other clients on the network.
The performance of the client's subsystems including its buffer cache, STREAMS resources, TCP/IP configuration, and the network adapter.
Other processes running on the client and server that compete for resources with NFS.

In practice, NFS servers feel the greatest stress. NFS client performance is directly dependent on the performance of the server and the network so you should examine these subsystems first if you experience poor client response.

Schematic diagram of how NFS works

The mechanism by which NFS is implemented is illustrated in ``Schematic diagram of how NFS works''. This figure shows a simplified version of how NFS operates and also illustrates the main features that affect performance. The NFS client is shown at the left-hand side; the NFS server with its local disk to the right. All the subsystems in the path traced between the application program running on the client and the disk on the server directly affect performance.

As for TCP/IP, NFS has been configured in this release to maximize performance. However, you may be able to further increase performance based on your system's needs.

Because NFS depends directly on STREAMS and TCP/IP resources, its performance is directly influenced by these subsystems. See ``STREAMS resources'' and ``TCP/IP resources'' for more information about examining the performance of these subsystems.