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

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 nfs4_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 the filesystem after changing this tunable. Only NFSv4
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 NFSv4 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.
2.1.39 nfs4_max_transfer_size
Description
The nfs4_max_transfer_size tunable specifies the maximum size of the data portion of NFSv4 READ,
WRITE and READDIR 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 nfs4_max_transfer_size tunable works in conjunction with the nfs4_bsize and
nfs4_max_transfer_size_cots tunables when determining the maximum size of these I/O requests. For
NFSv4 TCP traffic, the transfer size corresponds to the smallest value of nfs4_bsize,
nfs4_max_transfer_size, and nfs4_max_transfer_size_cots.
The nfs3_max_transfer_size tunable specifies the maximum size of the data portion of NFSv3
requests. For more information on the tunable, see nfs3_max_transfer_size.
Tested Values
Default: 1048576
Min: 4096
Max: 1048576