How to nfs mount on linux

How to Mount an NFS Share in Linux

Network File System (NFS) is a distributed file system protocol that allows you to share remote directories over a network. With NFS, you can mount remote directories on your system and work with the remote files as if they were local files.

On Linux and UNIX operating systems, you can use the mount command to mount a shared NFS directory on a particular mount point in the local directory tree.

In this tutorial, we will show you how to manually and automatically mount an NFS share on Linux machines.

Installing NFS Client Packages #

To mount an NFS share on a Linux system first you’ll need to install the NFS client package. The package name differs between Linux distributions.

Installing NFS client on Ubuntu and Debian:

sudo apt updatesudo apt install nfs-common

sudo yum install nfs-utils

Manually Mounting an NFS File Systems #

Mounting a remote NFS share is the same as mounting regular file systems.

To mount an NFS file system on a given mount point, use the mount command in the following form:

mount [OPTION. ] NFS_SERVER:EXPORTED_DIRECTORY MOUNT_POINT 

Use the steps below to manually mount a remote NFS share on your Linux system:

First, create a directory to serve as the mount point for the remote NFS share:

sudo mount -t nfs 10.10.0.10:/backups /var/backups

Once the share is mounted, the mount point becomes the root directory of the mounted file system.

When you are manually mounting the share, the NFS share mount does not persist after a reboot.

Automatically Mounting NFS File Systems with /etc/fstab #

Generally, you will want to mount the remote NFS directory automatically when the system boots.

The /etc/fstab file contains a list of entries that define where how and what filesystem will be mounted on system startup.

To automatically mount an NFS share when your Linux system starts up add a line to the /etc/fstab file. The line must include the hostname or the IP address of the NFS server, the exported directory, and the mount point on the local machine.

Use the following procedure to automatically mount an NFS share on Linux systems:

Set up a mount point for the remote NFS share:

#   10.10.0.10:/backups /var/backups nfs defaults 0 0

mount /var/backups mount 10.10.0.10:/backups

Unmounting NFS File Systems #

The umount command detaches (unmounts) the mounted file system from the directory tree.

To detach a mounted NFS share, use the umount command followed by either the directory where it has been mounted or remote share:

umount 10.10.0.10:/backups umount /var/backups

If the NFS mount have an entry in the fstab file, remove it.

The umount command will fail to detach the share when the mounted volume is in use. To find out which processes are accessing the NFS share, use the fuser command:

Once you find the processes you can stop them with the kill command and unmount the NFS share.

If you still have problems unmounting the share use the -l ( —lazy ) option which allows you to unmount a busy file system as soon as it is not busy anymore.

If the remote NFS system is unreachable, use the -f ( —force ) option to force an unmount.

Generally not a good idea to use the force option as it may corrupt the data on the file system.

Conclusion #

We have shown you how to mount and unmount a remote NFS share. The same commands apply for any Linux distribution, including Ubuntu, CentOS, RHEL, Debian and Linux Mint.

Feel free to leave a comment if you have any questions.

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How to Setup NFS (Network File System) on RHEL/CentOS/Fedora and Debian/Ubuntu

NFS (Network File System) is basically developed for sharing of files and folders between Linux/Unix systems by Sun Microsystems in 1980. It allows you to mount your local file systems over a network and remote hosts to interact with them as they are mounted locally on the same system. With the help of NFS, we can set up file sharing between Unix to Linux system and Linux to Unix system.

Benefits of NFS

1. NFS allows local access to remote files.
2. It uses standard client/server architecture for file sharing between all *nix based machines.
3. With NFS it is not necessary that both machines run on the same OS.
4. With the help of NFS we can configure centralized storage solutions.
5. Users get their data irrespective of physical location.
6. No manual refresh needed for new files.
7. Newer version of NFS also supports acl, pseudo root mounts.
8. Can be secured with Firewalls and Kerberos.

NFS Services

Its a System V-launched service. The NFS server package includes three facilities, included in the portmap and nfs-utils packages.

1. portmap : It maps calls made from other machines to the correct RPC service (not required with NFSv4).
2. nfs: It translates remote file sharing requests into requests on the local file system.
3. rpc.mountd: This service is responsible for mounting and unmounting of file systems.

Important Files for NFS Configuration

1. /etc/exports : Its a main configuration file of NFS, all exported files and directories are defined in this file at the NFS Server end.
2. /etc/fstab : To mount a NFS directory on your system across the reboots, we need to make an entry in /etc/fstab.
3. /etc/sysconfig/nfs : Configuration file of NFS to control on which port rpc and other services are listening.

Setup and Configure NFS Mounts on Linux Server

To setup NFS mounts, we’ll be needing at least two Linux/Unix machines. Here in this tutorial, I’ll be using two servers.

1. NFS Server: nfsserver.example.com with IP-192.168.0.100
2. NFS Client : nfsclient.example.com with IP-192.168.0.101

Installing NFS Server and NFS Client

We need to install NFS packages on our NFS Server as well as on NFS Client machine. We can install it via “yum” (Red Hat Linux) and “apt-get” (Debian and Ubuntu) package installers.

[[email protected] ~]# yum install nfs-utils nfs-utils-lib [[email protected] ~]# yum install portmap (not required with NFSv4)

[[email protected] ~]# apt-get install nfs-utils nfs-utils-lib

Now start the services on both machines.

[[email protected] ~]# /etc/init.d/portmap start [[email protected] ~]# /etc/init.d/nfs start [[email protected] ~]# chkconfig --level 35 portmap on [[email protected] ~]# chkconfig --level 35 nfs on

After installing packages and starting services on both the machines, we need to configure both the machines for file sharing.

Setting Up the NFS Server

First we will be configuring the NFS server.

Configure Export directory

For sharing a directory with NFS, we need to make an entry in “/etc/exports” configuration file. Here I’ll be creating a new directory named “nfsshare” in “/” partition to share with client server, you can also share an already existing directory with NFS.

Now we need to make an entry in “/etc/exports” and restart the services to make our directory shareable in the network.

[[email protected] ~]# vi /etc/exports /nfsshare 192.168.0.101(rw,sync,no_root_squash)

In the above example, there is a directory in / partition named “nfsshare” is being shared with client IP “192.168.0.101” with read and write (rw) privilege, you can also use hostname of the client in the place of IP in above example.

NFS Options

Some other options we can use in “/etc/exports” file for file sharing is as follows.

1. ro: With the help of this option we can provide read only access to the shared files i.e client will only be able to read.
2. rw: This option allows the client server to both read and write access within the shared directory.
3. sync: Sync confirms requests to the shared directory only once the changes have been committed.
4. no_subtree_check: This option prevents the subtree checking. When a shared directory is the subdirectory of a larger file system, 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.
5. no_root_squash: This phrase allows root to connect to the designated directory.

For more options with “/etc/exports“, you are recommended to read the man pages for export.

Setting Up the NFS Client

After configuring the NFS server, we need to mount that shared directory or partition in the client server.

Mount Shared Directories on NFS Client

Now at the NFS client end, we need to mount that directory in our server to access it locally. To do so, first we need to find out that shares available on the remote server or NFS Server.

[[email protected] ~]# showmount -e 192.168.0.100 Export list for 192.168.0.100: /nfsshare 192.168.0.101

Above command shows that a directory named “nfsshare” is available at “192.168.0.100” to share with your server.

Mount Shared NFS Directory

To mount that shared NFS directory we can use following mount command.

[[email protected] ~]# mount -t nfs 192.168.0.100:/nfsshare /mnt/nfsshare

The above command will mount that shared directory in “/mnt/nfsshare” on the client server. You can verify it following command.

[[email protected] ~]# mount | grep nfs sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw) nfsd on /proc/fs/nfsd type nfsd (rw) 192.168.0.100:/nfsshare on /mnt type nfs (rw,addr=192.168.0.100)

The above mount command mounted the nfs shared directory on to nfs client temporarily, to mount an NFS directory permanently on your system across the reboots, we need to make an entry in “/etc/fstab“.

Add the following new line as shown below.

192.168.0.100:/nfsshare /mnt nfs defaults 0 0

Test the Working of NFS Setup

We can test our NFS server setup by creating a test file on the server end and check its availability at nfs client side or vice-versa.

At the nfsserver end

I have created a new text file named “nfstest.txt’ in that shared directory.

[[email protected] ~]# cat > /nfsshare/nfstest.txt This is a test file to test the working of NFS server setup.

At the nfsclient end

Go to that shared directory in client server and you’ll find that shared file without any manual refresh or service restart.

[[email protected]]# ll /mnt/nfsshare total 4 -rw-r--r-- 1 root root 61 Sep 21 21:44 nfstest.txt [email protected] ~]# cat /mnt/nfsshare/nfstest.txt This is a test file to test the working of NFS server setup.

Removing the NFS Mount

If you want to unmount that shared directory from your server after you are done with the file sharing, you can simply unmount that particular directory with “umount” command. See this example below.

You can see that the mounts were removed by then looking at the filesystem again.

You’ll see that those shared directories are not available any more.

Important commands for NFS

Some more important commands for NFS.

1. showmount -e : Shows the available shares on your local machine
2. showmount -e: Lists the available shares at the remote server
3. showmount -d : Lists all the sub directories
4. exportfs -v : Displays a list of shares files and options on a server
5. exportfs -a : Exports all shares listed in /etc/exports, or given name
6. exportfs -u : Unexports all shares listed in /etc/exports, or given name
7. exportfs -r : Refresh the server’s list after modifying /etc/exports

This is it with NFS mounts for now, this was just a start, I’ll come up with more option and features of NFS in our future articles. Till then, Stay connected with Tecmint.com for more exciting and interesting tutorials in future. Do leave your comments and suggestions below in the comment box.

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