Managing NFS and NIS, 2nd Edition

Appendix C. Tunable Parameters

NFS client and server implementations tend to have lots of tunable parameters. This appendix summarizes some of the more important ones. Except as noted, the parameters are tuned by changing a parameter in the kernel, which requires setting a value in a file like /etc/system on Solaris 8. Note that while many NFS implementations share many of these parameters, the names of the parameters and the methods for setting them will vary between implementations. Table C-1 and Table C-2 summarize client and server tunables.

Table C-1. Client parameters

Parameter	Description	Caveats
clnt_max_conns	This parameter controls the number of connections the client will create between the client and a given server. In Solaris, the default is one. The rationale is that a single TCP connection ought to be sufficient to use the available bandwidth of network channel between the client and server. You may find this to not be the case for network media faster than the traditional 10Base T (10Mb per second). Note that this parameter is not in the Solaris nfs module, but it is in the kernel RPC module rpcmod.	At the time of this writing, the algorithm used to assign traffic to each connection was a simple round robin approach. You may find diminishing returns if you set this parameter higher than 2. This parameter is highly experimental.
clnt_idle_timeout	This parameter sets the number of milliseconds the NFS client will let a connection go idle before closing ...