NFS client freezes when NFS server system loses connection

SUSE Product Topics SLES Networking
1

I have a few servers on a LAN where I share out the /scratch folder on each via NFS-server,
and then on each server using NFS-client I mount the other’s scratch folders.
Problem arises when any one of the servers goes down, for example a reboot.
When an NFS-server is down, I cannot log in to any other system which is an NFS-client to that server.
Specifically:

  • an SSH connection to the NFS-client system can be established successfully,
  • you can enter your username and password,
  • but after entering your password you never get a prompt and the SSH connection is frozen.
  • After however long if the NFS-server system finally becomes available, you will get the prompt and be able to use that SSH connection.

How can I make it so that this does not happen?

my /etc/fstab file contains: hpc2:/scratch /scratch_hpc2 nfs defaults 0 0

the /etc/exports file on the nfs-server system contains: /scratch <ip_address>(rw,root_squash,sync,no_subtree_check)

I have set up NFS-server via YAST and I do NOT use NFSv4 nor do I use GSS security,

and /proc/mounts from an nfs-client system shows:

hpc2:/scratch /scratch_hpc2 nfs rw,relatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=<ip_address>,mountvers=3,mountport=40551,mountproto=udp,local_lock=none,addr=<ip_address> 0 0

2

On 19/09/16 16:14, ron7000 wrote:
[color=blue]

I have a few servers on a LAN where I share out the /scratch folder on
each via NFS-server,
and then on each server using NFS-client I mount the other’s scratch
folders.
Problem arises when any one of the servers goes down, for example a
reboot.
When an NFS-server is down, I cannot log in to any other system which is
an NFS-client to that server.
Specifically:

  • an SSH connection to the NFS-client system can be established
    successfully,
  • you can enter your username and password,
  • but after entering your password you never get a prompt and the SSH
    connection is frozen.
  • After however long if the NFS-server system finally becomes available,
    you will get the prompt and be able to use that SSH connection.

How can I make it so that this does not happen?

my /etc/fstab file contains: hpc2:/scratch /scratch_hpc2 nfs
defaults 0 0

the /etc/exports file on the nfs-server system contains: /scratch
<ip_address>(rw,root_squash,sync,no_subtree_check)

I have set up NFS-server via YAST and I do NOT use NFSv4 nor do I use
GSS security,

and /proc/mounts from an nfs-client system shows:

hpc2:/scratch /scratch_hpc2 nfs
rw,relatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=<ip_address>,mountvers=3,mountport=40551,mountproto=udp,local_lock=none,addr=<ip_address>
0 0[/color]

Duplicate of
https://forums.suse.com/showthread.php?8241-NFS-client-freezes-when-NFS-server-system-loses-connection

HTH.

Simon
SUSE Knowledge Partner

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