Managing NFS and KRPC Kernel Configurations in HP-UX 11i v3 (762807-001, March 2014)

The nfs_async_timeout tunable is dynamic. System reboot is not required to activate changes made to
this tunable. Changes made to the nfs_async_timeout tunable are applicable to all NFS mounted
filesystems.
Modifying the Value
Modify this tunable only if you can accurately predict the rate of asynchronous I/O. To avoid the
overhead of creating and deleting threads, increase the value of this tunable. To free up resources for
other subsystems, decrease the value of this tunable.
Setting the value of nfs_async_timeout to 0 causes threads to exit immediately when there are no
requests to process. HP recommends that you do not set the value of this tunable to 0.
2.1.2 nfs_disable_rddir_cache
Description
The nfs_disable_rddir_cache tunable controls the ability of a cache to hold responses from NFSv2
READDIR, NFSv3 READDIR, NFSv3 READDIRPLUS, and NFSv4 READDIR requests. When retrieving
directory information, this cache avoids over-the-wire calls to the server.
Tested Values
Default: 0 (NFS directory cache enabled)
Min: 0
Max: 1 (NFS directory cache disabled)
Restrictions on Changing
The nfs_disable_rddir_cache tunable is dynamic. System reboot is not required to activate changes
made to this tunable. Changes made to the value of this tunable are applicable to all NFS mounted
filesystems. Directory caching cannot be enabled or disabled on a per filesystem basis.
Modifying the Value
Modify the value of this tunable only if interoperability problems develop. These problems are caused
when a server does not update the modification time on a directory when a file or directory is created
or removed from it. For example, you might add a new directory and find that the modification time
has not been updated on the directory listing. Or, you might delete a directory and find that the name
of the removed directory still appears.
To enable caching for all NFS version mounted filesystems, set the value of this tunable to 0. To
disable caching for all three versions of NFS mounted filesystems, set the value of this tunable to 1.
Disabling caching can result in additional over-the-wire requests from the NFS client. If you disable the
[readdir] caching , you should also consider disabling the following tunables:
• nfs2_lookup_neg_cache
• nfs3_lookup_neg_cache
• nfs4_lookup_neg_cache