Gluster users - Jan 2015 - [Gluster-devel] lockd: server not responding, timed out

We have a 6 nodes gluster running ubuntu on xfs sharing gluster volumes over NFS
been running fine for 3 months.
We restarted glusterfs-server on one of the node and all NFS clients start
getting the " lockd: server  not responding, timed out" on
/var/log/messages

We are still able to read write but seems like process that require a persistent
file lock failed like database exports.

We have an interim fix to remount the NFS with nolock option but need to know
why that is necessary all in a sudden after a service glusterfs-server restart
on one of the gluster node

Thanks
Peter
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On Fri, Jan 23, 2015 at 11:50:26PM +0000, Peter Auyeung
wrote:
> We have a 6 nodes gluster running ubuntu on xfs sharing gluster
> volumes over NFS been running fine for 3 months.
> We restarted glusterfs-server on one of the node and all NFS clients
> start getting the " lockd: server  not responding, timed out" on
> /var/log/messages
> 
> We are still able to read write but seems like process that require a
> persistent file lock failed like database exports.
> 
> We have an interim fix to remount the NFS with nolock option but need
> to know why that is necessary all in a sudden after a service
> glusterfs-server restart on one of the gluster node
The cause that you need to mount wiht 'nolock' is that one server can
only have one NLM-service active. The Linux NFS-client uses the 'lockd'
kernel module, and the Gluster/NFS server provides its own lock manager.
To be able to use a lock manager, it needs to be registered at
rpcbind/portmapper. Only one lock manager can be registered at a time,
the 2nd one that tries to register will fail. In case the NFS-client has
registered the lockd kernel module as lock manager, any locking requests
to the Gluster/NFS service will fail and you will see those messages in
/var/log/messages.

This is one of the main reasons why it is not advised to access volumes
over NFS on a Gluster storage server. You should rather use the
GlusterFS protocol for mounting volumes locally. (Or even better,
seperate your storage servers from the application servers.)

HTH,
Niels
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