About NFS (Network File System) Mounts
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’.This tutorial requires 2 servers: one acting as the server and one as the client. We will set up the server machine first, followed by the client. The following IP addresses will refer to each one:
Master: 12.34.56.789
Client: 12.33.44.555
The system should be set up as root. You can access the root user by typing
sudo su-
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/nfsAfter completing those steps, it’s time to export the directories to the other VPS:
nano /etc/exportsAdd the following lines to the bottom of the file, sharing both directories with the client:
/home 12.33.44.555(rw,sync,no_root_squash,no_subtree_check) /var/nfs 12.33.44.555(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
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 filesmkdir -p /mnt/nfs/home mkdir -p /mnt/nfs/var/nfsThen go ahead and mount them
mount 12.34.56.789:/home /mnt/nfs/home mount 12.34.56.789:/var/nfs /mnt/nfs/var/nfsYou 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 12.34.56.789:/home 20G 948M 19G 5% /mnt/nfs/home 12.34.56.789:/var/nfs 20G 948M 19G 5% /mnt/nfs/var/nfsAdditionally, use the mount command to see the entire list of mounted file systems.
mountYour 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)
Testing the NFS Mount
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.Create a file in each directory to try it out:
touch /mnt/nfs/home/example /mnt/nfs/var/nfs/exampleYou should then be able to find the files on the Server in the /home and /var/nfs directories.
ls /home
ls /var/nfs/You can ensure that the mount is always active by adding the directories to the fstab file on the client. This will ensure that the mounts start up after the server reboots.
nano /etc/fstab
12.34.56.789:/home /mnt/nfs/home nfs auto,noatime,nolock,bg,nfsvers=3,intr,tcp,actimeo=1800 0 0 12.34.56.789:/var/nfs /mnt/nfs/var/nfs nfs auto,noatime,nolock,bg,nfsvers=3,intr,tcp,actimeo=1800 0 0You can learn more about the fstab options by typing in:
man nfsAny subsequent restarts will include the NFS mount—although the mount may take a minute to load after the reboot
You can check the mounted directories with the two earlier commands:
df -h
mount
Removing the NFS Mount
Should you decide to remove a directory, you can unmount it using the umount command:cd sudo umount /directory nameYou can see that the mounts were removed by then looking at the filesystem again.
df -hYou should find your selected mounted directory gone.
