Linux NFS Troubleshooting

Internal

• Linux NFS
• Linux NFS Installation

List Filesystems Exported by a NFS Server

exportfs: list filesystems exported by a NFS server

List Filesystems Mounted by a NFS Client

mount: list filesystems mounted by a NFS client

Useful Commands

verbose mount mount -v

showmount

rpcinfo

exportfs

Failures

mount hangs

I've seen cases when trying to mount a filesystem from other machine hangs if nfs is not started on that machine (service nfs start).

mount.nfs: access denied by server while mounting

I've also seen cases when I get the following error message when not using -t nfs, so use -t nfs:

mount.nfs: access denied by server while mounting f01:/opt/shared

mount(2): No such file or directory

mount -v yields:

mount.nfs: trying text-based options 'bg,vers=4,addr=172.31.20.184,clientaddr=172.31.21.24'
mount.nfs: mount(2): No such file or directory
...

I get this because I use the wrong exported path in /etc/fstab.

mount(2): No route to host

mount -v yields:

mount -v -t nfs 192.168.1.2:/volume3/dropbox /mnt/tmp
mount.nfs: timeout set for Sun Aug 21 00:44:48 2016
mount.nfs: trying text-based options 'vers=4,addr=192.168.1.2,clientaddr=192.168.1.9'
mount.nfs: mount(2): No route to host

This error means that the NFS client host is not getting a TCP/IP ACK back from the NFS server.

The problem went away after configuring iptables to allow all outbound traffic (see iptables Service Configuration).

mount(2): Permission denied

mount -v yields:

mount -v -t nfs 192.168.1.4:/volume3/dropbox /mnt/tmp
...
mount.nfs: mount(2): Permission denied
mount.nfs: access denied by server while mounting 192.168.1.4:/volume3/dropbox

The error is paired with the following on the server-side:

Aug 21 01:35:58 RackStation mountd[11206]: refused mount request from 192.168.1.9 for /volume3/dropbox (/volume3/dropbox): unmatched host

The root cause was the fact 192.168.1.9 was not specifically allowed access in the server's /etc/exports.

mount: wrong fs type, bad option, bad superblock on ...

mount: wrong fs type, bad option, bad superblock on 192.168.1.4:/volume1/nfstest,
      missing codepage or helper program, or other error
      (for several filesystems (e.g. nfs, cifs) you might
      need a /sbin/mount.<type> helper program)

Usually caused by the fact that the client libraries have not been installed. Fix it by installing client packages.

fcntl() failed with file ...: No locks available

Docker Storage Operations - NFS Volume Troubles