Implement a highly available NFS share
To implement a highly available NFS cluster, use SUSE Linux. High availability for NFS on Azure Virtual Machines on SUSE Linux Enterprise Server describes the setup. The NFS server is configured in a separate cluster and can be used by multiple SAP systems. The NFS server uses a dedicated virtual hostname and virtual IP addresses for every SAP system that uses this NFS server (on Azure, a load balancer is required to use a virtual IP address).
If you don't share the NFS cluster with any other HANA configurations outside the virtual network that hosts the SAP HANA instances, install it in the same virtual network but in its own subnet. Make sure to restrict traffic that can access the subnet by limiting it to the range of IP addresses assigned to hosts targeting the /hana/shared volume.