On-premises, you can use either HANA System Replication or use shared storage to establish high availability for SAP HANA. On Azure VMs HANA System Replication on Azure is the only supported High Availability function so far.
SAP HANA Replication consists of one primary node and at least one secondary node. Changes to the data on the primary node are replicated to the secondary node synchronously or asynchronously.
This article describes how to deploy the virtual machines, configure the virtual machines, install the cluster framework, install and configure SAP HANA System Replication. In the example configurations, installation commands etc. instance number 03 and HANA System ID HN1 is used.
Read the following SAP Notes and papers first