NFS

2011-06-07T13:29:51Z

Wizzy: Bind mounts

This page describes how to use '''NFS client''' inside a container.

{{Note|see [[NFS server inside container]] for info about nfsd.

Mounting filesystems from the '''hardware node''' can be performed more elegantly using [[Bind mounts]].}}

== Preparations ==
=== Prerequisites ===
You will need the following software:

# vzctl version 3.0.13 or higher (do <code>vzctl --version</code>)
# kernel version 2.6.18-028test006 or higher (2.6.18-028stab* will do), or any recent RHEL5-based or 2.6.20-based kernel.

Note: In all the kernels earlier than 028stab038, kernel NFS support can be given to a container by setting:

sunrpc.ve_allow_rpc = 1
fs.nfs.ve_allow_nfs = 1
kernel.ve_allow_kthreads = 1

This can be done by adding the above lines into /etc/sysctl.conf on the hardware node, and then running <code>sysctl -p</code>.

=== Prepare the HN ===

For NFS mounts to work in the containers with the RHEL5-based kernels you must enable kernel threads in the container by setting <code>kernel.ve_allow_kthreads=1</code> in <code>/etc/sysctl.conf</code>.

# modprobe nfs

You will probably want the nfs module to load automatically on reboots. One way to do this is to put the modprobe command in your /etc/rc.d/rc.local file:

modprobe nfs

=== Prepare the container ===
To allow a container to use NFS filesystem, you will need to start it with "nfs" feature enabled. If the container is running while you set the <code>--features nfs:on</code>, you will need to reboot it.

# vzctl set 101 --features "nfs:on" --save
# vzctl start 101

After this you may see nfs in <code>/proc/filesystems</code>
<pre>
# vzctl exec 101 cat /proc/filesystems
ext3
ext2
nodev rpc_pipefs
nodev proc
nodev nfs
nodev sysfs
nodev tmpfs
nodev devpts
</pre>

== Mounting NFS ==
Make sure that packages <code>nfs-utils</code> and <code>nfs-utils-lib</code> or similar are installed in a container.

Assuming that you already have NFS server set up at <code>192.168.0.1:/nfs_pub</code>, mounting will be simple
<pre>
# vzctl enter 100
# mkdir /nfs
# mount -t nfs 192.168.0.1:/nfs_pub /nfs
# cat /proc/mounts
simfs / simfs rw 0 0
proc /proc proc rw 0 0
sysfs /sys sysfs rw 0 0
devpts /dev/pts devpts rw 0 0
nfs /nfs nfs rw,vers=3,rsize=32768,wsize=32768,hard,proto=tcp,timeo=600,retrans=2,sec=sys,addr=192.168.0.1 0 0
</pre>

For more details on how to setup NFS mount, see [http://nfs.sourceforge.net/nfs-howto/ar01s04.html NFS-client HOWTO]

== Known issues ==
* There are quite a few parameters in NFS, so sometimes it doesn't work due to misconfiguration. We've created a separate page describing such situations: [[NFS doesn't work]].
* Package nfs-common can not be installed. Make sure you start <code>portmap</code> before trying to install nfs-common.

== See also ==
* [http://nfs.sourceforge.net/nfs-howto/ar01s04.html NFS-client HOWTO]

[[Category: HOWTO]]

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