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

The nfs3_pathconf_disable_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_pathconf_disable_cache tunable.
Modifying the Value
If you have an application that is making pathconf calls and needs real-time information from the
backend filesystem, turn off pathconf caching by setting the value of the tunable to 1.
2.1.33 nfs4_async_clusters
Description
The nfs4_async_clusters tunable controls the mix of asynchronous requests that are generated by the
NFSv4 client. There are four types of asynchronous requests:
• read-ahead
• putpage
• pageio
• readdir-ahead.
The client attempts to service these different requests without favoring one type of operation over
another. However some NFSv4 servers can take advantage of clustered requests from NFSv4 clients.
For instance, write gathering is a server function that depends on the NFSv4 client sending out
multiple WRITE requests in a short time span. If requests are taken out of the queue individually, the
client defeats this server functionality designed to enhance performance. The nfs4_async_clusters
tunable controls the number of outgoing requests for each type before changing types.
The nfs2_async_clusters tunable controls the mix of asynchronous requests generated by NFSv2
clients. The nfs3_async_clusters tunable controls the mix of asynchronous requests generated by
NFSv3 clients. For more information on these tunables, see:
• nfs2_async_clusters
• nfs3_async_clusters
Tested Values
Default: 1
Min: 0
Max: 10
Note: If the tunable is set to a value greater than 10
asynchronous requests, an informational warning is issued
at runtime. This value is outside the tested limits.
Restrictions on Changing
The nfs4_async_clusters tunable is dynamic. System reboot is not required to activate changes made
to this tunable. Any change made to the value of the tunable is effective immediately. However, the
cluster setting is per filesystem at mount time. The system administrator must unmount and re-mount
each filesystem after changing this tunable. Only NFSv4 mount points are affected by changing the
value of the nfs4_async_clusters tunable.