nfs2_max_threads(5)nfs2_max_threads(5)NAMEnfs2_max_threads - control the number of kernel threads that perform
asynchronous I/O for the NFS version 2 client
VALUES
Failsafe
Default
Allowed values
Recommended values
A warning will be issued at runtime if the tunable is set to a value
greater than 256 threads since this is beyond the tested limit. This
is not a serious warning but just an information message for the admin‐
istrator.
DESCRIPTION
controls the number of kernel threads that perform asynchronous I/O for
the NFS version 2 client. Since NFS is based on RPC and RPC is inher‐
ently synchronous, separate execution contexts are required to perform
NFS operations that are asynchronous from the calling thread. The
operations which can be executed asynchronously are read for read-
ahead, readdir for readdir read-ahead, and write for putpage and pageio
requests.
Who Is Expected to Change This Tunable?
The distributed file system administrator should examine this value
depending on the network bandwidth available.
Restrictions on Changing
The tunable is dynamic; however, the number of threads for a file sys‐
tem is set when the file system is mounted. To affect a particular file
system, unmount and mount the file system after changing this parame‐
ter.
When Should the Value of This Tunable Be Raised?
If the network is very high bandwidth and the client and server have
sufficient resources, increase this value to more effectively utilize
the available network bandwidth, the client resources, and the server
resources.
What Are the Side Effects of Raising the Value?
An increase in the system resources and the possibility that (see
nkthread(5)) may need to be increased. The total number of asynchronous
threads for NFS version 2 and NFS version 3 mount points cannot exceed
20% of the available threads defined by NFS mounts will fail if the NFS
mount command cannot guarantee the ability to create the maximum number
of threads for that mount point.
When Should the Value of This Tunable Be Lowered?
In a very low bandwidth network, decrease this value so that the NFS
client does not overload the network.
What Are the Side Effects of Lowering the Value?
Decreasing this value may impact NFS performance.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parame‐
ter may be removed or have its meaning changed in future releases of
HP-UX.
Installation of optional kernel software, from HP or other vendors, may
cause changes to tunable parameter values. After installation, some
tunable parameters may no longer be at the default or recommended val‐
ues. For information about the effects of installation on tunable val‐
ues, consult the documentation for the kernel software being installed.
For information about optional kernel software that was factory
installed on your system, see at
AUTHOR
was developed by Sun Microsystems, Inc.
SEE ALSOkctune(1M), sam(1M), gettune(2), settune(2), nfs3_max_threads(5),
nfs4_max_threads(5), nkthread(5).
Tunable Kernel Parameters nfs2_max_threads(5)