Wednesday, 24 February 2016

How to Guide for Tier Based HANA System-Replication

SAP HANA System Replication is used in most of the SAP HANA implmentation for HA or DR scnearios.

In this blog, is more for the technology consultants, a bit inclined to technical people.

I have installed three HANA instances with same SID and instance number. So won't be talking any thing on installing SAP HANA systems.

SAP HANA Certifications and Material

Make sure three hosts have different hostname and different IP's.

Change the bewlow parameters:
SSL in  global.ini  with value "systempki".
enable_ssl in global.ini to on

Change these parameters in all the required HANA systems.

Backup the HANA system which you want as a primary. Without a full databack we cannot enable system replication.

SAP HANA Certifications and Material

SAP HANA System Replication

use the command "hdbnsutil -sr_state" to see the status of system replication.

SAP HANA System-Replication

As we have't registered the secondary system, it doesn't show SITEB.

To enable the replication, we need to stop the seconday systems

Register the secondary system:

SAP HANA Material and Certifications

SAP HANA Certifications and Material

Always use the hostname to configure system replication. We use virtual hostname for a dedicated communication between these systems.

Replication status can also be checked in Studio

SAP HANA System Replication

This completes the TIER1 replication of SAP HANA systems

Enabling tier 2 replication:
In this scenario, data will be replicated from Seconday system.

We have used mode of replication as asynchronus for tier2  replication.

SAP HANA Certifications and Material

Registering the third site:

SAP HANA Replications

Site A:

SAP HANA Certifications and Material

Site B:

SAP HANA System Replications

Site C:
SAP HANA Certifications and Material

Perfom takeover:
Automatic failover is not supported by default, it is possible to setup auto takeover using SUSE packages and OS specific configuration.
I will detail the standard manual take over procedure:

SAP HANA Certifications and System Replications

SAP HANA System and Certifications

I have then disabled the replication on the primary server.

SAP HANA System-Replication

SAP HANA System-Replication and Certifications

Source: scn.sap.com