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

Modifying the Value
If filesystems are mounted read-only on the client, and applications running on the client need to
immediately see any filesystem changes made on the server, disable this tunable. If you disable this
tunable, also consider disabling the nfs_disable_rddir_cache tunable. For more information, see
nfs_disable_rddir_cache.
2.1.14 nfs2_max_threads
Description
The nfs2_max_threads tunable controls the number of kernel threads that perform asynchronous I/O
for NFSv2 filesystems. The operations executed asynchronously are read, readdir, and write.
The nfs3_max_threads tunable controls the number of kernel threads that perform asynchronous I/O
for NFSv3 filesystems. The nfs4_max_threads tunable controls the number of kernel threads that
perform asynchronous I/O for NFSv4 filesystems. For more information on these tunables, see:
• nfs3_max_threads
• nfs4_max_threads
Tested Values
Default: 8
Min: 0
Max: 256
Note: If the tunable is set to a value greater than 256
threads, an informational warning is issued at runtime. Any
value greater than 256 is outside the tested limits.
Restrictions on Changing
The nfs2_max_threads tunable is dynamic. System reboot is not required to activate changes made to
this tunable. However, the number of threads is set per filesystem at mount time. The system
administrator must unmount and re-mount each filesystem after changing this tunable. Only NFSv2
mount points are affected by changing the value of this tunable.
Modifying the Value
Before modifying the value of this tunable, examine the available network bandwidth. If the network
has high available bandwidth and the client and server have sufficient CPU and memory resources,
increase the value of this tunable. This increase enables you to effectively utilize the available network
bandwidth as well as the client and server resources. However, the total number of asynchronous
threads for NFSv2 cannot exceed 20% of the available nkthreads. NFS mounts fail if the mount
command cannot guarantee the ability to create the maximum number of threads for that mount point.
If the network has low available bandwidth, decrease the value of this tunable. This decrease will
ensure that the NFS client does not overload the network. Decreasing the value can impact NFS
performance because it limits the number of asynchronous threads that can be spawned, and thus
limits the number of simultaneous asynchronous I/O requests.
2.1.15 nfs2_nra
Description
The nfs2_nra tunable controls the number of read-ahead operations queued by NFSv2 clients when