I have a couple of servers in a VPC in Amazon EC2. One of them acts as a NFS server, and one of them as a client.

I recently noticed a problem in the client that after a reboot, it would reject all SSH connections, presumably because SSH was not running. After transferring the EBS volume to another instance and taking a peek inside, I commented out the NFS line in /etc/fstab and tried attaching it back to the server and booting it. Lo and behold, I was able to connect with SSH.

It seems that having the following line in my fstab is breaking everything on boot: /mnt/shared nfs auto 0 0

Why is this causing SSH to fail to start? How can I have NFS automatically mount on boot without breaking networking/SSH on the system?

I've checked that sudo mount -a works properly, so it seems that there isn't an inherent problem in the fstab command. What's breaking and how can I fix it?

  • Does disabling automounting, then manually mounting it after SSH has loaded successfully also break SSH? – Chris Down Apr 18 '13 at 4:13
  • Nope, it only breaks on boot when it's in fstab. – Naftuli Kay Apr 18 '13 at 4:32
  • Does the SSH init script actually run? – Chris Down Apr 18 '13 at 5:04
  • What ami are you using? The latest RHEL or something else? I found a bug in the latest RHEL image in rc.local that was causing ssh to fail to start on reboot. After I fixed that things were good. A bad nfs config should not conflict with SSH as long as you're not clobbering your home directory preventing access to your ssh credentials – John Apr 18 '13 at 15:56
  • Ubuntu 12.04 64bit. – Naftuli Kay Apr 18 '13 at 17:56

You need to add one more option when mounting nfs , we always use this

Example /mnt/shared nfs _netdev,noatime,intr,auto 0 0

These are mount options : 'noatime' improves access rate, and 'auto' tells the Rpi to aumount the NFS shares on startup.

from man mount

_netdev The filesystem resides on a device that requires network access (used to prevent the system from attempting to mount these filesystems until the network has been enabled on the system).

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  • Even with that exact line in my fstab, SSH doesn't start up. Comment it out, and it starts. – Naftuli Kay Apr 18 '13 at 21:55
  • what is sequence in fstab, is that nfs entry at last ? – Rahul Patil Apr 19 '13 at 3:25
  • Yes, it's at the last entry in fstab. – Naftuli Kay Apr 19 '13 at 4:24
  • have you find any error in logs /var/log/syslog or /var/log/messages – Rahul Patil Apr 19 '13 at 4:38
  • Nope, nothing significant in there. – Naftuli Kay Apr 19 '13 at 23:02

Try using nobootwait or nofail as mount options in the fstab.

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Same problem with nfs shares mounted on a remote server. nfs is going through openvpn.

I tried load of things, nothing worked, included hints above. options in fstab like _netdev,ro,noauto,nofail,x-systemd.automount,x-systemd.requires=openvpn.service,x-systemd.device-timeout=30 0 0 did not work.

In rc3.d I tried different services order...

The only very dirty solution I found was to use _netdev,ro,noauto,nofail 0 0 option in fstab just to make sure it ignores those nfs shares if they do not mount correctly at boot up and added a line in rc.local to mount the shares like mount

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