HANA 2.0 System Replication - HA/DR

SAP HANA 2.0 System Replication for High Availability and Disaster Recovery

In this blog we are going to talk about the step by step procedures for SAP HANA 2.0 System Replication setup for HA/DR.

You can use below tool to configure the HANA System replication:
SAP HANA Cockpit 2.0
SAP HANA Studio
Command line tool hdbnsutil

In this blog we are using HANA Studio for system replication.

Pre-requisite

1. Primary and Secondary database systems should be installed and configured , verify both are up and running independently.
2. In HANA 2.0 System PKI SSFS key and data should be copy from primary to secondary systems.
3. Primary and Secondary HANA database should be on same size and configuration
4. Primary and Secondary HANA database should be on same HANA version
5. Primary and Secondary HANA database should have same SID and instance number
6. Primary and Secondary HANA database should be installed on different host.
7. Primary and Secondary HANA database should be on same network segment
8. Initial Data backup must be performed on the Primary database before the system replication can be activated.
9. System DB and all tenant database much be backed up at Primary Database node.

Install SAP HANA 2.0 Database on Primary node

Maintain the Host entry file for both nodes in all the servers



Download SAP HANA 2.0 DVD from Service Market place , extract the DVD and transfer via SFTP to HANA server

Run the ./hdblcm from the DVD















HANA Database installation finished successfully on Primary node

Check the HANA running services using HDB info command 

Install SAP HANA 2.0 Database on Secondary node

Download SAP HANA 2.0 DVD from Service Market place , extract the DVD and transfer via SFTP to HANA server

Run the ./hdblcm from the DVD 

HANA Database installation finished successfully on Secondary node

Check the HANA running services using HDB info command 

Setting up SAP HANA Database System Replication Using SAP HANA studio

Create Data backup for System DB and Tenant Database on Primary node

Login into System DB of Primary database server using system id and password

Right mouse click on Primary database and select "Backup and Recovery"--> Backup System Database-->Back up System Database

Right mouse click on Primary database and select "Backup and Recovery"--> Backup System Database-->Back up Tenant Database

Copy PKI SSFS key and data files from Primary database to Secondary Database

Stop Secondary database 

Copy SSFS key and data files to Secondary node from below location

/usr/sap/HDB/SYS/global/security/rsecssfs/key

/usr/sap/HDB/SYS/global/security/rsecssfs/data

Start Secondary Database and check the running process

Enable HANA system Replication on Primary database node

Right mouse-click on Primary System --> Configuration and Monitoring --> Configure System Replication , Check the radio button to enable system replication

Click Next



Enter Site name for Primary Database node and click next



Click Finish

Stop the secondary system with right mouse-click on Secondary System --> Configuration and Monitoring --> Stop System





Click Ok

Register the secondary database: Right mouse-click on Secondary System --> Configuration and Monitoring --> Configure System Replication … Check radio button “Register secondary system”

 Click Next

Enter Site name for Secondary database node ,
Select replication and operation mode as per your requirement.
Enter Primary database host name

If you are configuring HANA system replication for HA then you select replication mode sync or syncmem
If you are configuring HANA system replication for DR then you select replication mode async

In HANA 2.0 SPS00,  HANA system replication can be configured as Active/Active (read enable) system.

if you want to configure Active/Active system then you need to select operation mode as logreplay_readaccess.

To configure logreplay_readaccess operation mode you need to use HANA Cockpit 2.0 or command line tool hdbnsutil , this operation mode configuration is not supported through HANA Studio

Click Finish

HANA System Replication setup finished successfully

Once the secondary system is automatically started, the replication process will also start automatically

Check the replication status in Primary database --> HANA Studio --> Landscape --> System Replication

Replication is initializing

Replication between primary and secondary is now Active

After a new tenant DB was created in a SAP HANA Multitenant Database Containers system running with SAP HANA system replication, a backup of this new tenant DB is necessary. Otherwise the replication for this tenant DB will not start.

Takeover 

The following steps are performed:
Trigger a takeover to the secondary system in the event of a disaster.
Register the former primary system as new secondary when it becomes available again.

Procedure for Takeover 

On secondary system: Perform a takeover with right mouse-click on Secondary System --> Configuration and Monitoring --> Configure System Replication

Select "Perform takeover"

Click Next

Click Finish

When the former primary is available again it can be registered as secondary

Stop original (former) primary system.

 
On original (former) primary system: Register system as secondary with right mouse-click on former Primary System --> Configuration and Monitoring --> Configure System Replication

Select "Register secondary System"

You will be informed that this system used to be the primary system before

Enter Site name for Formal Primary database node ,
Select replication and operation mode.
Enter New Primary database host name

Click Next

Disabling HANA System Replication for Maintenance 

Stop the secondary system with right mouse-click on Secondary System --> Configuration and Monitoring à Stop System 

On secondary system: Unregister system replication for the secondary system with right mouse-click on Secondary System --> Configuration and Monitoring --> Configure System Replication

Select radio button “Unregister secondary System”

On primary system: Disable system replication on the primary system with right mouse-click on Primary System --> Configuration and Monitoring --> Configure System Replication

Select Radio button “Disable System Replication”