Learn how to resolve mount.nfs: Stale file handle error on the Linux platform. This is a Network File System error that can be resolved from the client or server end.

When you are using the Network File System in your environment, you must have seen mount.nfs: Stale file handle error at times. This error denotes that the NFS share is unable to mount since something has changed since the last good known configuration.

Whenever you reboot the NFS server or some of the NFS processes are not running on the client or server or share is not properly exported at the server; these can be reasons for this error. Moreover, it’s irritating when this error comes to a previously mounted NFS share. Because this means the configuration part is correct since it was previously mounted. In such case once can try the following commands:

Make sure NFS service are running good on client and server.

#  service nfs status
rpc.svcgssd is stopped
rpc.mountd (pid 11993) is running...
nfsd (pid 12009 12008 12007 12006 12005 12004 12003 12002) is running...
rpc.rquotad (pid 11988) is running...

If NFS share currently mounted on the client, then un-mount it forcefully and try to remount it on NFS client. Check if its properly mounted by df command and changing directory inside it.

# umount -f /mydata_nfs
# mount -t nfs server:/nfs_share /mydata_nfs
#df -k
------ output clipped -----
server:/nfs_share 41943040  892928  41050112   3% /mydata_nfs

In above mount command, server can be IP or hostname of NFS server.

If you are getting error while forcefully un-mounting like below :

# umount -f /mydata_nfs
umount2: Device or resource busy
umount: /mydata_nfs: device is busy
umount2: Device or resource busy
umount: /mydata_nfs: device is busy

Then you can check which all processes or users are using that mount point with lsof command like below:

# lsof |grep mydata_nfs
lsof: WARNING: can't stat() nfs file system /mydata_nfs
      Output information may be incomplete.
su         3327      root  cwd   unknown                                                   /mydata_nfs/dir (stat: Stale NFS file handle)
bash       3484      grid  cwd   unknown                                                   /mydata_nfs/MYDB (stat: Stale NFS file handle)
bash      20092  oracle11  cwd   unknown                                                   /mydata_nfs/MPRP (stat: Stale NFS file handle)
bash      25040  oracle11  cwd   unknown                                                   /mydata_nfs/MUYR (stat: Stale NFS file handle)

If you see in above example that 4 PID are using some files on said mount point. Try killing them off to free mount point. Once done you will be able to un-mount it properly.

Sometimes it still gives the same error for mount command. Then try mounting after restarting NFS service at the client using the below command.

#  service nfs restart
Shutting down NFS daemon:                                  [  OK  ]
Shutting down NFS mountd:                                  [  OK  ]
Shutting down NFS quotas:                                  [  OK  ]
Shutting down RPC idmapd:                                  [  OK  ]
Starting NFS services:                                     [  OK  ]
Starting NFS quotas:                                       [  OK  ]
Starting NFS mountd:                                       [  OK  ]
Starting NFS daemon:                                       [  OK  ]
Starting RPC idmapd:                                       [  OK  ]

Also read : How to restart NFS step by step in HPUX

Even if this didn’t solve your issue, final step is to restart services at the NFS server. Caution! This will disconnect all NFS shares which are exported from the NFS server. All clients will see the mount point disconnect. This step is where 99% of you will get your issue resolved. If not then NFS configurations must be checked, provided you have changed configuration and post that you started seeing this error.

Outputs in above post are from RHEL6.3 server. Drop us your comments related to this post.