Basically I'm looking for "multipath nfs". I want a classic network filesystem but with multiple servers mounted at the clients to a single mount point and it should handle a server failure with transparent failover among the servers without any delay. Load balancing and performance is not an issue. Sync among the servers can be done outside of this solution, it could even be read-only for the normal clients through this interface.
I prefer to avoid GFS, Lustre, AFS, IP round robin and "complicated" things like those.
Do you know a simple solution for this problem?