Home > Storage > PowerScale (Isilon) > Product Documentation > Protocols > Dell Multipath Client Driver: Installation and Configuration Guide > Configuring the client NFS mounts
As mentioned previously, the multipath driver allows Linux clients to mount a PowerScale cluster’s NFS exports over NFS v3, NFS v4.1, or NFS v4.2 over RDMA.
The principle NFS mount options of interest with the multipath client driver are:
Mount option | Description |
nconnect | Allows the admin to specify the number of TCP connections the client can establish between itself and the NFS server. It works with remoteports to spread load across multiple target interfaces. |
localports | Mount option that allows a client to use its multiple NICs to multiplex I/O. |
localports_failover | Mount option allowing transports to temporarily move from local client interfaces that are unable to serve NFS connections. |
proto | The underlying transport protocol that the NFS mount will use. Typically, either TCP or RDMA. |
remoteports | Mount option that allows a client to target multiple servers/ NICS to multiplex I/O. Remoteports spreads the load to multiple file handles instead of taking a single file handle to avoid thrashing on locks. |
version | The version of the NFS protocol that is to be used. The multipath driver supports NFSv3, NFSv4.1, and NFSv4.2. Note that NFSv4.0 is unsupported. |
These options allow the multipath driver to be configured such that an IO stream to a single NFS mount can be spread across a number of local (client) and remote (cluster) network interfaces (ports). Nconnect allows you to specify how many socket connections you want to open to each combination of local and remote ports.
Following are some example topologies and NFS client configurations using the Dell multipath driver.
In this example, NFSv3 with RDMA is used to spread traffic across all the front-end interfaces (remoteports) on the PowerScale cluster:
# mount -o proto=rdma,port=20049,vers=3,nconnect=18,remoteports=10.231.180.95- 10.231.180.98 10.231.180.98:/ifs/data /mnt/test
As you can see, this driver can be incredibly powerful given its ability to multipath comprehensively. Clearly, there are many combinations of local and remote ports and socket connections that can be configured.
This next example uses NFSv3 with RDMA across three ‘localports’ (client) and with 8 socket connections to each:
# mount -o proto=rdma,port=20049,vers=3,nconnect=24,localports=10.219.57.225- 10.219.57.227, remoteports=10.231.180.95-10.231.180.98 10.231.180.98:/ifs/data /mnt/test
The final configuration example specifies NFSv4.1 with RDMA using a high connection count to target multiple nodes (remoteports) on the cluster:
# mount -t nfs –o proto=rdma,port=20049,vers=4.1,nconnect=64,remoteports=10.231.180.95- 10.231.180.98 10.231.180.98:/ifs/data /mnt/test
In this case, 16 socket connections will be opened to each of the four specified remote (cluster) ports for a total of 64 connections.
Note: The Dell multipath driver has a hard-coded limit of 64 nconnect socket connections per mount.
Behind the scenes, the driver uses a network map to store the local and remote port and nconnect socket configuration.
The multipath driver supports both IPv4 and IPv6 addresses for local and remote port specification. If a specified IP address is unresponsive, the driver will remove the offending address from its network map.
Note: The Dell multipath driver supports NFSv3, NFSv4.1, and NFSv4.2 but is incompatible with NFSv4.0.