NAME
nfs3_max_transfer_size — control the data portion size of a NFS version 3 read, write, readdir, or readdirplus request
VALUES
Allowed values
Minimum: 4096
Maximum: MAXINT
Recommended values
A warning will be issued at runtime if the tunable is set to a value greater
than 1048576 since this is outside the tested limits.
This is not a serious warning but
just an information message for the administrator.
DESCRIPTION
nfs3_max_transfer_size
controls the maximum size of the data portion of a NFS version 3 read, write,
readdir, or readdirplus request. This parameter controls both the maximum
size of a request that the server returns as well as the maximum size
of a request that the client generates.
Who Is Expected to Change This Tunable?
Distributed file system administrators should examine this value
if they want to decrease or increase the default size of a NFS packet.
Restrictions on Changing
The
nfs3_max_transfer_size
tunable is dynamic; however, the transfer size 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.
The actual NFS version 3 transfer size is controlled by these tunable
parameters:
nfs3_bsize,
nfs3_max_transfer_size,
and
nfs3_max_transfer_size_cots.
The actual transfer size will depend on the tunable with the smallest
value. For NFS version 3 TCP traffic increase
nfs3_max_transfer_size,
nfs3_max_transfer_size_cots,
and
nfs3_bsize
to the same value to increase the transfer size. To decrease the
transfer size, just changing
nfs3_bsize
is sufficient.
When Should the Value of This Tunable Be Raised?
An increase in the transfer size will result in fewer requests to the NFS
server at the expense of system resources on both the
NFS client and NFS server.
What Are the Side Effects of Raising the Value?
Setting the limit too large might result in errors from UDP and communication
problems between the client and the server.
When Should the Value of This Tunable Be Lowered?
In the event of NFS communication failures, the value should be
changed back to the default value.
What Are the Side Effects of Lowering the Value?
An increase in NFS version 3 network traffic caused by an
increase in the number of I/O requests.
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 tunable values, consult the documentation
for the kernel software being installed.
For information about optional kernel software that was
factory installed on your system, see
HP-UX Release Notes
at
http://docs.hp.com.
AUTHOR
nfs3_max_transfer_size
was developed by Sun Microsystems, Inc.
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