NFS

This page describes how to mount NFS partition inside a container.

Contents

NFS server

Currently OpenVZ kernel doesn't include kernel NFS server support. However you are still able to use user space NFS server inside container.

NFS client

Preparations

Prerequisites

You will need the following software:

1. vzctl version 3.0.13 or higher (do vzctl --version)
2. 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 sysctl -p.

Debian Notes

Debian Etch still uses vzctl version 3.0.11 and so NFS client support is not yet available. Lenny presently has version 3.0.18.

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 kernel.ve_allow_kthreads=1 in /etc/sysctl.conf.

# 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 --features nfs:on, you will need to reboot it.

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

After this you may see nfs in /proc/filesystems

# vzctl exec 101 cat /proc/filesystems
        ext3
        ext2
nodev   rpc_pipefs
nodev   proc
nodev   nfs
nodev   sysfs
nodev   tmpfs
nodev   devpts

Mounting NFS

Make sure that packages nfs-utils and nfs-utils-lib or similar are installed in a container.

Assuming that you already have NFS server set up at 192.168.0.1:/nfs_pub, mounting will be simple

# 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

For more details on how to setup NFS mount, see 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.

See also

• NFS-client HOWTO