nfs4_nra(5)

NAME

nfs4_nra — control the number of read-ahead operations queued by the NFS version 4 client when sequentially accessing a file

VALUES

Failsafe

4

Default

4

Allowed values

Minimum: 0

Maximum: MAXINT

Recommended values

A warning will be issued at runtime if the tunable is set to a value greater than 16 since this is beyond the tested limit. This is not a serious warning but just an information message for the administrator.

DESCRIPTION

nfs4_nra controls the number of read-ahead operations that are queued by the NFS version 4 client when sequential access to a file is discovered. These read-ahead operations increase concurrency and read throughput. Each read-ahead request is generally for 32768 bytes of file data.

Who Is Expected to Change This Tunable?

The distributed file system administrator should examine this value depending on network bandwidth and memory pressure on the client.

Restrictions on Changing

The nfs4_nra tunable is dynamic; tuning will take effect immediately on the running system.

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?

Tuning incorrectly based on network bandwidth can cause performance problems.

When Should the Value of This Tunable Be Lowered?

In a very low bandwidth network, decrease this value so the NFS client does not overload the network.

What Are the Side Effects of Lowering the Value?

Tuning incorrectly based on network bandwidth can cause performance problems.

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_nra was developed by Sun Microsystems, Inc.