Documentation: NFS/RDMA instructions for 2.6.25-rc1

Add some instructions for using the new NFS/RDMA features.
Signed-off-by: James Lentini <jlentini@netapp.com>
Cc: Roland Dreier <rdreier@cisco.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

Documentation/filesystems/nfs-rdma.txt

+################################################################################
+#									       #
+#				NFS/RDMA README				       #
+#									       #
+################################################################################
+
+ Author: NetApp and Open Grid Computing
+ Date: February 25, 2008
+
+Table of Contents
+~~~~~~~~~~~~~~~~~
+ - Overview
+ - Getting Help
+ - Installation
+ - Check RDMA and NFS Setup
+ - NFS/RDMA Setup
+
+Overview
+~~~~~~~~
+
+  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
+
+                nfs-rdma-devel@lists.sourceforge.net
+
+  mailing list.
+
+Installation
+~~~~~~~~~~~~
+
+  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 (http://fedora.redhat.com/).
+
+  - Install nfs-utils-1.1.1 or greater on the client
+
+    An NFS/RDMA mount point can only be obtained by using the mount.nfs
+    command in nfs-utils-1.1.1 or greater. To see which version of mount.nfs
+    you are using, type:
+
+    > /sbin/mount.nfs -V
+
+    If the version is less than 1.1.1 or the command does not exist,
+    then you will need to install the latest version of nfs-utils.
+
+    Download the latest package from:
+
+    http://www.kernel.org/pub/linux/utils/nfs
+
+    Uncompress the package and follow the installation instructions.
+
+    If you will not be using GSS and NFSv4, the installation process
+    can be simplified by disabling these features when running configure:
+
+    > ./configure --disable-gss --disable-nfsv4
+
+    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.
+
+    NOTE: mount.nfs and therefore nfs-utils-1.1.1 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-1.1.1 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 2.6 Linux
+    kernel can be found at:
+
+    ftp://ftp.kernel.org/pub/linux/kernel/v2.6/
+
+    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
+    card:
+
+    > 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:
+
+    > cat /sys/class/infiniband/driverX/ports/1/state
+    4: ACTIVE
+
+    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):
+
+    host1> ifconfig ib0 a.b.c.x
+    host2> ifconfig 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.
+
+NFS/RDMA Setup
+~~~~~~~~~~~~~~
+
+  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 format have been tested:
+
+    /vol0   10.97.103.47(rw,async) 192.168.0.47(rw,async,insecure,no_root_squash)
+
+    Here the first IP address is the client's Ethernet address and the second
+    IP address is the clients IPoIB address.
+
+ Each time a machine boots:
+
+  - Load and configure the RDMA drivers
+
+    For InfiniBand using a Mellanox adapter:
+
+    > modprobe ib_mthca
+    > modprobe ib_ipoib
+    > ifconfig ib0 a.b.c.d
+
+    NOTE: 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:
+
+    > modprobe svcrdma
+
+    Regardless of how the server was built (module or built-in), start the server:
+
+    > /etc/init.d/nfs start
+
+    or
+
+    > service nfs start
+
+    Instruct the server to listen on the RDMA transport:
+
+    > echo rdma 2050 > /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:
+
+    > modprobe xprtrdma.ko
+
+    Regardless of how the client was built (module or built-in), issue the mount.nfs command:
+
+    > /path/to/your/mount.nfs <IPoIB-server-name-or-address>:/<export> /mnt -i -o rdma,port=2050
+
+    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!