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

Note: The nfs3_max_transfer_size tunable affects every
NFSv3 filesystem. To control the transfer sizes of specific
NFS filesystems, use the rsize and wsize mount options.
Refer to the mount_nfs(1M) man page for more information.
2.1.29 nfs3_max_transfer_size_clts
Description
The nfs3_max_transfer_size_clts 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 the server returns as well as the maximum size of the request the client generates over a
connectionless transport, such as UDP.
The nfs3_max_transfer_size_clts tunable works in conjunction with the nfs3_bsize,
nfs3_max_transfer_size, and nfs3_max_transfer_size_cots 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 NFSv3 UDP traffic, the
transfer size corresponds to the smallest value of nfs3_bsize, nfs3_max_transfer_size, and
nfs3_max_transfer_size_clts.
Tested Values
Default: 32768
Min: 4096
Max: 32768
Note: If the tunable is set to a value greater than 32768, an
informational warning is issued at runtime. Any value
greater than 32768 is outside the tested limits. The value of
the tunable must be a power of 2.
Restrictions on Changing
The nfs3_max_transfer_size_clts tunable is dynamic. System reboot is not required to activate changes
made to this tunable. However, the transfer size for a filesystem is set when the filesystem is mounted.
In order to affect a specific filesystem, the system administrator must unmount and re-mount the
filesystem after changing this tunable. Only NFSv3 mount points are affected by changing the value
of this tunable.
Modifying the Value
For NFS/UDP Filesystems:
To increase the size of NFSv3 UDP requests, set the nfs3_bsize, nfs3_max_transfer_size, and
nfs3_max_transfer_size_clts tunables to the same value. Otherwise, the transfer size will default to the
smallest value of these three tunables.