Managing NFS and KRPC Kernel Configurations in HP-UX 11i v2 (November 2013)

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.

For NFS/UDP Filesystems:

To increase the size of NFSv3 UDP requests, set the nfs3_max_transfer_size and

nfs3_max_transfer_size_clts tunables to the same value. Otherwise, the transfer size defaults to the

smaller value of these two tunables.

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_max_transfer_size,

nfs3_max_transfer_size_clts, or nfs3_max_transfer_size_cots

tunable value was changed while NFS filesystems were

mounted. You must unmount and re-mount the NFS

filesystem to use the new value.

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) manpage for more information.

2.1.21 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 and 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_max_transfer_size tunable

when determining the maximum size of these I/O requests. For NFSv3 TCP traffic, the transfer size

corresponds to the smaller value of nfs3_max_transfer_size and nfs3_max_transfer_size_clts.