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 1048576,
an informational warning is issued at runtime. Any value
greater than 1048576 is outside the tested limits. The value
of the tunable must be a power of 2.
Restrictions on Changing
The nfs3_max_transfer_size_cots 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 particular 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/TCP Filesystems:
To increase the transfer size of NFSv3 TCP requests, set the nfs3_bsize, nfs3_max_transfer_size, and
nfs3_max_transfer_size_cots tunables to the same value. Otherwise, the transfer size will default to the
smallest value of these three tunables. For example, if 1 MB transfers are desired, all three tunables
must be set to at least 1 MB. If two of the tunables are set to 1 MB and the third is set to 32 KB, the
transfer size will be 32 KB since that is the smallest value of the three tunables.
To decrease the size of NFSv3 TCP requests, decrease the value of the nfs3_max_transfer_size_cots
tunable. For example, to decrease the size of I/O requests on all NFSv3 TCP filesystems to 8 KB, set
the value of nfs3_max_transfer_size_cots to 8192.
Caution: If the NFS client is experiencing NFS READ failures
and the system is reporting "NFS read failed for server
<servername>: RPC: Can’t decode result" errors, this is an
indication that the nfs3_bsize, nfs3_max_transfer_size,
nfs3_max_transfer_size_clts, or nfs3_max_transfer_size_cots
tunable value was changed while NFS filesystems were
mounted. The system administrator must unmount and re-
mount the NFS filesystem to use the new value.
Note: The nfs3_max_transfer_size_cots 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.