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Setting up NFS/RDMA
NetApp and Open Grid Computing (May 29, 2008)
.. warning::
This document is probably obsolete.
This document describes how to install and setup the Linux NFS/RDMA client
and server software.
The NFS/RDMA client was first included in Linux 2.6.24. The NFS/RDMA server
was first included in the following release, Linux 2.6.25.
In our testing, we have obtained excellent performance results (full 10Gbit
wire bandwidth at minimal client CPU) under many workloads. The code passes
the full Connectathon test suite and operates over both Infiniband and iWARP
RDMA adapters.
Getting Help
If you get stuck, you can ask questions on the mailing list.
These instructions are a step by step guide to building a machine for
use with NFS/RDMA.
- Install an RDMA device
Any device supported by the drivers in drivers/infiniband/hw is acceptable.
Testing has been performed using several Mellanox-based IB cards, the
Ammasso AMS1100 iWARP adapter, and the Chelsio cxgb3 iWARP adapter.
- Install a Linux distribution and tools
The first kernel release to contain both the NFS/RDMA client and server was
Linux 2.6.25 Therefore, a distribution compatible with this and subsequent
Linux kernel release should be installed.
The procedures described in this document have been tested with
distributions from Red Hat's Fedora Project (
- Install nfs-utils-1.1.2 or greater on the client
An NFS/RDMA mount point can be obtained by using the mount.nfs command in
nfs-utils-1.1.2 or greater (nfs-utils-1.1.1 was the first nfs-utils
version with support for NFS/RDMA mounts, but for various reasons we
recommend using nfs-utils-1.1.2 or greater). To see which version of
mount.nfs you are using, type:
.. code-block:: sh
$ /sbin/mount.nfs -V
If the version is less than 1.1.2 or the command does not exist,
you should install the latest version of nfs-utils.
Download the latest package from:
Uncompress the package and follow the installation instructions.
If you will not need the idmapper and gssd executables (you do not need
these to create an NFS/RDMA enabled mount command), the installation
process can be simplified by disabling these features when running
.. code-block:: sh
$ ./configure --disable-gss --disable-nfsv4
To build nfs-utils you will need the tcp_wrappers package installed. For
more information on this see the package's README and INSTALL files.
After building the nfs-utils package, there will be a mount.nfs binary in
the utils/mount directory. This binary can be used to initiate NFS v2, v3,
or v4 mounts. To initiate a v4 mount, the binary must be called
mount.nfs4. The standard technique is to create a symlink called
mount.nfs4 to mount.nfs.
This mount.nfs binary should be installed at /sbin/mount.nfs as follows:
.. code-block:: sh
$ sudo cp utils/mount/mount.nfs /sbin/mount.nfs
In this location, mount.nfs will be invoked automatically for NFS mounts
by the system mount command.
.. note::
mount.nfs and therefore nfs-utils-1.1.2 or greater is only needed
on the NFS client machine. You do not need this specific version of
nfs-utils on the server. Furthermore, only the mount.nfs command from
nfs-utils-1.1.2 is needed on the client.
- Install a Linux kernel with NFS/RDMA
The NFS/RDMA client and server are both included in the mainline Linux
kernel version 2.6.25 and later. This and other versions of the Linux
kernel can be found at:
Download the sources and place them in an appropriate location.
- Configure the RDMA stack
Make sure your kernel configuration has RDMA support enabled. Under
Device Drivers -> InfiniBand support, update the kernel configuration
to enable InfiniBand support [NOTE: the option name is misleading. Enabling
InfiniBand support is required for all RDMA devices (IB, iWARP, etc.)].
Enable the appropriate IB HCA support (mlx4, mthca, ehca, ipath, etc.) or
iWARP adapter support (amso, cxgb3, etc.).
If you are using InfiniBand, be sure to enable IP-over-InfiniBand support.
- Configure the NFS client and server
Your kernel configuration must also have NFS file system support and/or
NFS server support enabled. These and other NFS related configuration
options can be found under File Systems -> Network File Systems.
- Build, install, reboot
The NFS/RDMA code will be enabled automatically if NFS and RDMA
are turned on. The NFS/RDMA client and server are configured via the hidden
SUNRPC_XPRT_RDMA config option that depends on SUNRPC and INFINIBAND. The
value of SUNRPC_XPRT_RDMA will be:
#. N if either SUNRPC or INFINIBAND are N, in this case the NFS/RDMA client
and server will not be built
#. M if both SUNRPC and INFINIBAND are on (M or Y) and at least one is M,
in this case the NFS/RDMA client and server will be built as modules
#. Y if both SUNRPC and INFINIBAND are Y, in this case the NFS/RDMA client
and server will be built into the kernel
Therefore, if you have followed the steps above and turned no NFS and RDMA,
the NFS/RDMA client and server will be built.
Build a new kernel, install it, boot it.
Check RDMA and NFS Setup
Before configuring the NFS/RDMA software, it is a good idea to test
your new kernel to ensure that the kernel is working correctly.
In particular, it is a good idea to verify that the RDMA stack
is functioning as expected and standard NFS over TCP/IP and/or UDP/IP
is working properly.
- Check RDMA Setup
If you built the RDMA components as modules, load them at
this time. For example, if you are using a Mellanox Tavor/Sinai/Arbel
.. code-block:: sh
$ modprobe ib_mthca
$ modprobe ib_ipoib
If you are using InfiniBand, make sure there is a Subnet Manager (SM)
running on the network. If your IB switch has an embedded SM, you can
use it. Otherwise, you will need to run an SM, such as OpenSM, on one
of your end nodes.
If an SM is running on your network, you should see the following:
.. code-block:: sh
$ cat /sys/class/infiniband/driverX/ports/1/state
where driverX is mthca0, ipath5, ehca3, etc.
To further test the InfiniBand software stack, use IPoIB (this
assumes you have two IB hosts named host1 and host2):
.. code-block:: sh
host1$ ip link set dev ib0 up
host1$ ip address add dev ib0 a.b.c.x
host2$ ip link set dev ib0 up
host2$ ip address add dev ib0 a.b.c.y
host1$ ping a.b.c.y
host2$ ping a.b.c.x
For other device types, follow the appropriate procedures.
- Check NFS Setup
For the NFS components enabled above (client and/or server),
test their functionality over standard Ethernet using TCP/IP or UDP/IP.
We recommend that you use two machines, one to act as the client and
one to act as the server.
One time configuration:
- On the server system, configure the /etc/exports file and start the NFS/RDMA server.
Exports entries with the following formats have been tested::
The IP address(es) is(are) the client's IPoIB address for an InfiniBand
HCA or the client's iWARP address(es) for an RNIC.
.. note::
The "insecure" option must be used because the NFS/RDMA client does
not use a reserved port.
Each time a machine boots:
- Load and configure the RDMA drivers
For InfiniBand using a Mellanox adapter:
.. code-block:: sh
$ modprobe ib_mthca
$ modprobe ib_ipoib
$ ip li set dev ib0 up
$ ip addr add dev ib0 a.b.c.d
.. note::
Please use unique addresses for the client and server!
- Start the NFS server
If the NFS/RDMA server was built as a module (CONFIG_SUNRPC_XPRT_RDMA=m in
kernel config), load the RDMA transport module:
.. code-block:: sh
$ modprobe svcrdma
Regardless of how the server was built (module or built-in), start the
.. code-block:: sh
$ /etc/init.d/nfs start
.. code-block:: sh
$ service nfs start
Instruct the server to listen on the RDMA transport:
.. code-block:: sh
$ echo rdma 20049 > /proc/fs/nfsd/portlist
- On the client system
If the NFS/RDMA client was built as a module (CONFIG_SUNRPC_XPRT_RDMA=m in
kernel config), load the RDMA client module:
.. code-block:: sh
$ modprobe xprtrdma.ko
Regardless of how the client was built (module or built-in), use this
command to mount the NFS/RDMA server:
.. code-block:: sh
$ mount -o rdma,port=20049 <IPoIB-server-name-or-address>:/<export> /mnt
To verify that the mount is using RDMA, run "cat /proc/mounts" and check
the "proto" field for the given mount.
Congratulations! You're using NFS/RDMA!