Network File System (NFS) allows remote hosts to mount file systems over a network and interact with those file systems as though they are mounted locally. This can be useful for sharing files and data across machines.

If you have NFS set up on your Linux machines, you may want to check on the status of your NFS mounts to understand what is currently mounted, confirm connectivity, and troubleshoot any issues. Checking NFS mounts in Linux is easy to do with just a few simple commands.

Use the mount Command

The most straightforward way to check NFS mounts on Linux is by using the mount command.

To see all mounts, including NFS mounts:

mount

This will display all mounts in the standard mount output format:

nfs-server:/export/directories on /mount/point type nfs (rw,relatime,vers=3,rsize=32768,wsize=32768,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.1.10,mountvers=3,mountport=20048,mountproto=udp,local_lock=none,addr=192.168.1.10)

The key pieces here are:

• nfs-server:/export/directories - The NFS export on the server

• /mount/point - Where the share is mounted locally

• type nfs - Identifies this as an NFS mount

You can also filter mount output to show only NFS mounts using grep:

mount | grep nfs

This can help simplify the output and focus only on the NFS mounts.

Use the df Command

The df (disk free) command can also display NFS mount information in Linux. The -T option can be used to specify the filesystem type:

df -T | grep nfs

Much like the filtered mount output, this will only show filesystems mounted via NFS, verifying your remote shares.

Check Mounts in /etc/mtab

The /etc/mtab file records mounted filesystems and can be checked manually:

cat /etc/mtab

Here you would again look for shares mounted with nfs as the filesystem type.

Identify Mount Issues

If you see any issues indicating a mount failure or connectivity problems to the NFS share, there are a few things you can try.

Unmount and remount:

sudo umount /mountpoint
sudo mount /mountpoint

Check NFS server and port connectivity:

telnet nfs-server 2049

Verify NFS exports on the server:

showmount -e nfs-server

Restart the NFS server service if needed.

Be sure to check your network and firewall rules as well if you see persistent mount issues.

Automate with a Monitoring Script

To simplify monitoring your NFS mounts, you can create a script to output status. For example:

#!/bin/bash

SERVER="nfs-server"
MOUNTPOINT="/mountpoint"

if ! mount | grep $MOUNTPOINT > /dev/null; then
  echo "$MOUNTPOINT not mounted" >&2
  exit 1
fi  

if ! showmount -e $SERVER>$MOUNTPOINT; then
  echo "$SERVER not responding" >&2 
  exit 1
fi  

echo "$SERVER mounted on $MOUNTPOINT"

This will output an error if the mount directory is not actually mounted or if the NFS server is not reachable, making problems clear. Otherwise, it reports the mount as active.

NFS Mount Tips

Here are some additional tips for working with and checking NFS mounts in Linux:

• Check the contents of /etc/fstab to see which NFS mounts are configured to mount automatically at boot time.

• The findmnt command can provide output similar to mount if you prefer an alternate view.

• After making changes to NFS mounts, always double-check with df or mount to validate the expected status.

• Monitor free disk space on mounted NFS shares with df -h to catch capacity issues before they become problems.

• Configure test clients to automount shares from a central NFS server to test connectivity before deploying changes across your environment.

Key Advantages of NFS Mounts

There are good reasons to consider using NFS mounts on Linux systems:

• File system sharing - Centralize data and access across mixed OS environments.

• User transparent access - Access shared directories seamlessly as local mounts.

• Easy administration - Add, move, and replicate data easily on the server side.

• Read/write support - Mounts support full read and write permissions.

• Industry-standard - Backed by a proven, widely adopted protocol.

With proper configuration and occasional monitoring, you can unlock excellent file sharing with your Linux hosts via NFS while keeping tabs on its status.

Summary

NFS mounting provides an easy way to share storage on a network. By mounting network exports to local directories, users can seamlessly access these remote directories as needed.

There are a few simple commands on Linux to check the status of your NFS mounts:

• Use mount and filter with grep to see only NFS mounts

• Check df -T output for shares mounted with NFS

• View local mount records in /etc/mtab

• Verify server exports and connectivity to identify issues

• Consider writing a script to monitor mounts automatically

NFS can facilitate very convenient centralized file storage for Linux users if monitored closely. Hopefully, these commands give you easy ways to keep an eye on your NFS mounts.

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