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

To decrease the size of NFSv3 UDP requests, decrease the value of the nfs3_max_transfer_size_clts
tunable. For example, to decrease the size of I/O requests on all NFSv3 UDP filesystems to 8 KB, set
the value of nfs3_max_transfer_size_clts to 8192.
Caution: HP strongly discourages increasing
nfs3_max_transfer_size_clts above the default value of
32768 as this can cause NFS/UDP requests to fail. Also, 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_clts 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.
2.1.30 nfs3_max_transfer_size_cots
Description
The nfs3_max_transfer_size_cots 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
connection-oriented transport, such as TCP.
The nfs3_max_transfer_size_cots tunable works in conjunction with the nfs3_bsize,
nfs3_max_transfer_size, 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 NFSv3 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_cots tunable specifies the maximum size of the data portion of NFSv4
requests. For more information on the tunable, see nfs4_max_transfer_size_cots.
Tested Values
Default: 1048576
Min: 4096
Max: 1048576