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nfs3_bsize.5 (2010 09)

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nfs3_bsize(5) nfs3_bsize(5)
(Tunable Kernel Parameters)
NAME
nfs3_bsize - controls the logical block size used by NFS version 3 clients
VALUES
Failsafe
32768
Default
32768
Allowed values
Minimum: 4096
Maximum: MAXINT
Recommended Values
A warning will be issued at runtime if this tunable is set to a value greater than 1048576 bytes since this
is beyond the tested limit. This is not a serious warning but just an information message for the adminis-
trator.
DESCRIPTION
nfs3_bsize controls the logical block size used by NFS version 3 clients. This block size represents the
amount of data the client attempts to read from or write to the server when it does I/O.
Who Is Expected to Change This Tunable?
The distributed file system administrator should examine this value and change it if a larger transfer size
is needed.
Restrictions on Changing
The
nfs3_bsize tunable is dynamic; however, the logical block size setting for a file system is set when
the file system is mounted. In order to affect a particular file system, it is necessary to unmount and
mount the file system after changing this parameter.
When Should the Value of This Tunable Be Raised?
Increase this parameter and also the
nfs3_max_transfer_size
and
nfs3_max_transfer_size_cots
parameters if larger transfers are desired.
What Are the Side Effects of Raising the Value?
More kernel memory is used to manage the transfer buffer.
When Should the Value of This Tunable Be Lowered?
Lower the value of this tunable if smaller transfer sizes are desired.
What Are the Side Effects of Lowering the Value?
Setting this value to less than 32 KB will increase the number of requests to the NFS server.
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 parame-
ter 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://www.hp.com/go/hpux-core-docs.
AUTHOR
nfs3_bsize was developed by Sun Microsystems, Inc.
SEE ALSO
kctune(1M), sam(1M), gettune(2), settune(2), nfs3_max_transfer_size(5), nfs3_max_transfer_size_cots(5),
nfs4_bsize(5), values(5).
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

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