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

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 nfs3_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 NFSv3
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 NFSv3 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.
2.1.28 nfs3_max_transfer_size
Description
The nfs3_max_transfer_size tunable specifies the maximum size of the data portion of NFSv3 READ,
WRITE, READDIR, and READDIRPLUS requests. This parameter controls both the maximum size of the
data that the server returns and the maximum size of the request the client generates.
The nfs3_max_transfer_size tunable works in conjunction with the nfs3_bsize,
nfs3_max_transfer_size_cots, and nfs3_max_transfer_size_clts tunables when determining the
maximum size of these I/O requests. For NFSv3 TCP traffic, the transfer size corresponds to the
smallest value of nfs3_bsize, nfs3_max_transfer_size, and nfs3_max_transfer_size_cots. For UDP
traffic, the transfer size corresponds to the smallest value of nfs3_bsize, nfs3_max_transfer_size, and
nfs3_max_transfer_size_clts.
The nfs4_max_transfer_size tunable specifies the maximum size of the data portion of NFSv4
requests. For more information on the tunable, see nfs4_max_transfer_size.
Tested Values
Default: 1048576
Min: 4096
Max: 1048576