I want to correct that statement of @AlainTansi . SMB users that connects with SMB2 and above should sustain the session loss due to the durable handles feature. The continues availability features mentioned does not improve the resiliency for most clients, and should only be used for supported ones such SQL and Hyper-V.
The behaviour can change from one software to another. And with the way the network is built. Occasional warning/error messages displayed to the users can happen, and process that try to write in given moment can timeout.
"ONTAP 9 does not support persistent handles for use cases other than Microsoft Hyper-V over SMB and SQL Server over SMB".
For durable handles:
"When a LIF is migrated between nodes, client sessions become disconnected.SMB 1 is unable to prevent the lock state from being lost during these network outages, but SMB 2+clients,by using durable handles,can re establish disconnected sessions and maintain non disruptive operations. When an SMB 2 client opens a file and establishes a lock, a durable handle is created that records session details, the most important of which is the server that is associated with it. If the session is interrupted, the file remains open on the client, and the durable handle is used to reconnect the session."
@ShahbazRiaz I don't have a working lab at the moment to test the NFS command for you. Maybe open a new thread on it if you don't find any existing ones...
I don't have other recommendations for NFS except of:
1. look for supportability in the IMT and any notes there (support.netapp.com/matrix),
For NFS sessions, you can read on this TR on page 62 https://www.netapp.com/us/media/tr-4067.pdf For the "nfs connected-clients show" syntax, you should be running in diag mode ::> set d ::*>nfs connected-clients show
My only guest you should still get the error is if NFS is not license on the cluster.
Are you having an HA-pair ? What SMB and NFS versions are you using ?
Due to the nature of the SMB protocol, all SMB sessions except for SMB 3.0 sessions connected to shares with the Continuous Availability property set, will be disruptive. SMB 1.0 and SMB 2.x sessions cannot reconnect after a takeover event. Therefore, takeover is disruptive and some data loss could occur.
For details about CIFS and NFS sessions use the following commands ::> vserver cifs session show ::> vserver nfs show
You can also check the session uptime by running the following; ::> system node run -node <node_name> -command uptime