Thank you for your answer.

On Shares used in the NFS failover, only NFS and data Replication can be used.
So you need to stop failover to take a backup.
Thats not possible. If you stop failover, all virtuall interfaces will be down!!
So you can't stop failover!! So you can't do local backups!!
As only data replication is possible on shares that are in NFS failover is running( replication is like taking a backup for your data, but in the real time, sure it is recommended to have a backup too for very critical data, but you need to stop the Failover in that case).
How should I make backups?? Is the only way to mount the nfs share on a other maschine and do the backup (with a tools like zmanda, ... )?? Can you recommend a tool??

I have another problem.
If I enable Nas failover, I can't change any nfs settings. Although some shares are not marked for failover. Is that right?? So if I activated nfs failover and create a new nfs share on a new lv, I can't ativate nfs!!

Regards,
Erik