NFS- Network File System

NFS mounts work to share a directory between several virtual servers. This has the advantage of saving disk space, as the home directory is only kept on one virtual private server, and others can connect to it over the network. When setting up mounts, NFS is most effective for permanent fixtures that should always be accessible.

Setup

An NFS mount is set up between at least two virtual servers. The machine hosting the shared network is called the server, while the ones that connect to it are called ‘clients’.


Setting Up the NFS Server

Step One—Download the Required Software

Start off by using apt-get to install the nfs programs.

apt-get install nfs-kernel-server portmap


Step Two—Export the Shared Directory

The next step is to decide which directory we want to share with the client server. The chosen directory should then be added to the /etc/exports file, which specifies both the directory to be shared and the details of how it is shared.

 

Suppose we wanted to share two directories: /home and /var/nfs.

 

Because the /var/nfs/ does not exist, we need to do two things before we can export it.

 

First, we need to create the directory itself:
mkdir /var/nfs/

 

Second, we should change the ownership of the directory to the user, nobody and the group, no group. These represent the default user through which clients can access a directory shared through NFS.

 

Go ahead and chown the directory:
chown nobody:nogroup /var/nfs

 

After completing those steps, it’s time to export the directories to the other VPS:
nano /etc/exports

 

Add the following lines to the bottom of the file, sharing both directories with the client:
/home           <client ip>(rw,sync,no_root_squash,no_subtree_check)
/var/nfs        <client ip>(rw,sync,no_subtree_check)

 

These settings accomplish several tasks:
  • rw: This option allows the client server to both read and write within the shared directory
  • sync: Sync confirms requests to the shared directory only once the changes have been committed.
  • no_subtree_check: This option prevents the subtree checking. When a shared directory is the subdirectory of a larger filesystem, nfs performs scans of every directory above it, in order to verify its permissions and details. Disabling the subtree check may increase the reliability of NFS, but reduce security.
  • no_root_squash: This phrase allows root to connect to the designated directory

 

Once you have entered in the settings for each directory, run the following command to export them:
exportfs -a

Setting Up the NFS Client

Step One—Download the Required Software

Start off by using apt-get to install the nfs programs.

apt-get install nfs-common portmap


Step Two—Mount the Directories

Once the programs have been downloaded to the the client server, create the directories that will contain the NFS shared files

mkdir -p /mnt/nfs/home
mkdir -p /mnt/nfs/var/nfs

 

Then go ahead and mount them
mount <server ip>:/home /mnt/nfs/home
mount <server ip>:/var/nfs /mnt/nfs/var/nfs

 

You can use the df -h command to check that the directories have been mounted. You will see them last on the list.
df -h

 

Filesystem             Size  Used Avail Use% Mounted on
/dev/sda                20G  948M   19G   5% /
udev                   119M  4.0K  119M   1% /dev
tmpfs                   49M  208K   49M   1% /run
none                   5.0M     0  5.0M   0% /run/lock
none                   122M     0  122M   0% /run/shm
<server ip>:/home      20G  948M   19G   5% /mnt/nfs/home
<server ip>:/var/nfs   20G  948M   19G   5% /mnt/nfs/var/nfs

 

Additionally, use the mount command to see the entire list of mounted file systems.
mount

 

Your list should look something like this:
/dev/sda on / type ext4 (rw,errors=remount-ro,barrier=0) [DOROOT]
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
rpc_pipefs on /run/rpc_pipefs type rpc_pipefs (rw)
12.34.56.789:/home on /mnt/nfs/home type nfs (rw,vers=4,addr= 12.34.56.789,clientaddr=12.33.44.555)
12.34.56.789:/var/nfs on /mnt/nfs/var/nfs type nfs (rw,vers=4,addr=12.34.56.78,clientaddr=12.33.44.555)

Note:
Once you have successfully mounted your NFS directories, you can test that they work by creating files on the Client and checking their availability on the Server.
 

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