systemd seems to ignore _netdev option for NFS in Ubuntu 16.04

Question

I have the following mount for NFS in /etc/fstab:

192.168.1.6:/var/share /media/share nfs hard,intr,retrans=10,timeo=10000000,_netdev 0 0

On reboot my system hangs; turns out it's the mount as proved by systemd-analyze blame.

The status:

● media-share.mount - /media/share
   Loaded: loaded (/etc/fstab; bad; vendor preset: enabled)
   Active: failed (Result: timeout) since Tue 2016-04-26 21:13:43 EDT; 6min ago
    Where: /media/share
     What: 192.168.1.6:/var/share
     Docs: man:fstab(5)
           man:systemd-fstab-generator(8)
  Process: 1071 ExecMount=/bin/mount 192.168.1.6:/var/share /media/share -t nfs -o hard,intr,retrans=10,timeo=10000000,_netdev (code=kille

Apr 26 21:12:12 j-Lemur systemd[1]: Mounting /media/share...
Apr 26 21:13:42 j-Lemur systemd[1]: media-share.mount: Mounting timed out. Stopping.
Apr 26 21:13:42 j-Lemur systemd[1]: Mounted /media/share.
Apr 26 21:13:43 j-Lemur systemd[1]: media-share.mount: Unit entered failed state.

This appears to be a bug?

After logging in and running systemctl restart media-share.mount it is fixed (because the network is available now).

Answer 1

I had the same problem.

There's some info on the Ubuntu Community Help Wiki here suggesting it is intentional behaviour by Ubuntu 16:

Under NFSv3 (type nfs) the _netdev option will tell the system to wait to mount until the network is available. With a type of nfs4 this option is ignored, but can be used with mount -O _netdev in scripts later. Currently Ubuntu Server does not come with the scripts needed to auto-mount nfs4 entries in /etc/fstab after the network is up.

My solution was to the add "vers=3" before "_netdev", forcing the connection to use NFS v3. Obviously this might not help in your case, if you are relying on NFS v4.

Other options could include AutoFS or shell scripting.