nfs2_max_threads(5) File Formats Manual nfs2_max_threads(5)
NAME
nfs2_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 administrator.
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
inherently 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 system is set when the file system is mounted. To affect a particular
file system, unmount and mount the file system after changing this parameter.
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 parameter 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 values. For information about the effects of installation on tun-
able values, 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 ALSO
kctune(1M), sam(1M), gettune(2), settune(2), nfs3_max_threads(5), nfs4_max_threads(5), nkthread(5).
Tunable Kernel Parameters nfs2_max_threads(5)