Managing NFS and KRPC Kernel Configurations in HP-UX 11i v2 (Oct 2008)

Modifying the Value
If biod processes are running on the client, enable this tunable to avoid unnecessary cache purging
for sequential read, write, and lseek operations on an NFS-mounted file. If the cached data is purged
unnecessarily, more over-the-wire (OTW) calls are needed. Enabling this tunable can improve the
performance of the NFS client.
Disable this tunable to purge the cache for a sequential read, write, and lseek operation, resulting in
more OTW calls. This may degrade the performance of the NFS client.
Depending on the system configuration and applications used, modifying this tunable can result in
increased or decreased performance. You must analyze your applications and check whether
enabling this tunable improves the performance of the NFS client.
This tunable is not available in the next release of HP-UX. Starting with the HP-UX 11i v3 release, the
WCC check is enabled by default and is not user-configurable.
2.1.15 nfs3_do_symlink_cache
Description
The nfs3_do_symlink_cache tunable caches the contents of symbolic links in NFSv3 mounted
filesystems. If the server changes the contents of a symbolic link, and if either the time stamps are not
updated or the granularity of the time stamp is too large, then the changes become visible to the client
after a long time interval.
The nfs2_do_symlink_cache tunable caches the contents of symbolic links in NFSv2 mounted
filesystems. For more information on this tunable, see
nfs2_do_symlink_cache.
Tested Values
Default: 1 (Symbolic link cache is enabled)
Min: 0 (Symbolic link cache is disabled)
Max: 1
Restrictions on Changing
The nfs3_do_symlink_cache
tunable is dynamic. System reboot is not required to activate changes
made to this tunable. Only NFSv3 mount points are affected by changing the value of the
nfs3_do_symlink_cache tunable.
Modifying the Value
Enable this tunable to cache the contents of symbolic links. Because the client uses the cached version,
changes made to the contents of the symbolic link file are not immediately visible to applications
running on the client.
To make the changes made to the symbolic link file immediately visible to applications on the client,
disable this tunable. Disabling the tunable can result in more over-the-wire requests from the client if
filesystems are mounted with NFSv3 and contain symbolic links.
2.1.16 nfs3_dynamic
Description
The nfs3_dynamic tunable controls the dynamic retransmission feature for NFSv3 mounted filesystems.
The dynamic retransmission feature is designed to reduce NFS retransmissions by monitoring server
response time and adjusting read and write transfer sizes on NFSv3 mounted filesystems using
connectionless transports such as UDP.
The nfs2_dynamic tunable controls the dynamic retransmission feature for NFSv2 mounted filesystems.
For more information on the tunable, see
nfs2_dynamic.
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