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nfs4_bsize(5)

Tunable Kernel Parameters
HP-UX 11i Version 3: February 2007
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NAME

nfs4_bsize — control the logic block size used by NFS version 4 clients

VALUES

Failsafe

32768

Default

32768

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 bytes since this is beyond the tested limit. This is not a serious warning but just an information message for the administrator.

DESCRIPTION

nfs4_bsize controls the logical block size used by NFS version 4 clients. This block size represents the amount of data the client attempts to read from or write to the server when it needs to do 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 nfs4_bsize tunable is dynamic; however, the logical block size setting 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?

Increase this parameter and also the nfs4_max_transfer_size and nfs4_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 then 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 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

nfs4_bsize was developed by Sun Microsystems, Inc.

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