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SAP HANA HA and DR using System Replication

SAP HANA System Replication is a reliable high availability and disaster recovery solution that provides continuous synchronization of a HANA database to a secondary location either in the same data center or remote site.
System Replication is a standard SAP HANA feature. In this method, all data is replicated to the secondary site and data is pre-loaded into memory on the secondary site which helps to reduce the recovery time objective (RTO) significantly. So in case of a failover, the secondary site will be able to take over without even performing a HANA DB (re)start and will work as primary DB straightaway.
Once the system replication is configured properly, each HANA internal process (nameserver, indexserver etc) connects to its counterpart on the secondary site, and all logged changes in the primary location are replicated to secondary site continuously through persisted redo logs. While system replication is running, the secondary site is on standby mode with data already pre-loaded into memory, and ready to take over. Please note that, in this scenario secondary site does not accept any requests or make any changes on DB.
Figure 1: SAP HANA System Replication Overview
Network requirements
Network requirements are usually overlooked when it comes to System Replication but it is very important to have a good network and bandwidth in place, especially for remote disaster recovery site. Because the data is continuously replicated to the secondary site, network bandwidth and latency should be sufficient to fulfil requirements. To estimate the network requirements, you need to know the size of data and log that are generated during your daily workload so you can make an informed decision.
You can use HANA_Replication_SystemReplication_Status.sql attached to SAP Note 1969700 – SQL Statement Collection for SAP HANA. On the primary system, simply choose System Information tab and right-click in the “Name” column and choose Import SQL Statements, choose SQLStatements.zip attached to that note, and you will get complete set of useful SQL statements.

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