Best practices for implementing Geo-Redundancy

Last Updated : Sep 26, 2022 |

MSSQL Availability Group Listener FQDN

Ensure that you configure the POM servers in all the Data Centers to point to the MSSQL Availability Group Listener FQDN. Do not configure the POM servers to point to the MSSQL database server ip/hostname/FQDN.

Primary Database Node

Ensure that the MSSQL database node for an Active Data center is always the primary replica.

If there is active Data Center-1 to standby Data Center-2 failover, you must first execute the database failover. After completing the database failover execution, ensure that the database node on the Data Center-2 is now the primary replica. Then, execute the POM failover where the Data Center-1 is marked as standby, and the Data Center-2 is marked as active.

Availability mode in Database

You must configure the MSSQL primary replica and secondary replica with the asynchronous commit mode. This allows the primary replica to commit the transaction without waiting for the secondary replica. This is helpful when the primary replica and the secondary replica are placed at a significant distance, and the performance on the active POM Data Center is more important than the data synchronization.

Availability-Group Failover

Ensure that you configure the database with Manual failover, not with Automatic failover. The failover behavior for each secondary replica depends on which availability replica is currently the primary replica.

Refer to Microsoft documentation for:
  • Additional details on “Always On” feature.

  • Help on how to configure availability to asynchronous commit mode for all POM database nodes.

  • Help on configuring failover mode to manual for all the POM database nodes configured in the availability group.

POM Servers

Use the Add POM Server option to add the POM servers of all the Data centers. Only after you add all the POM servers, execute the Data center configuration to add the Data Center. For example, If Data Center-1 has three POM servers, use the Add POM Server option to sequentially add the three POM servers. On the Data Center Configuration page, use the Add Data Center option to create Data Center-1.

Later, to add a Data Center-2 with three POM servers, use the Add POM Server option to add all the three POM servers. Then, on the Data Center Configuration page, you can use the Add Data Center option to create Data Center-2.

Note:
  • The name of all the POM servers across all the Data Centers should be unique.

  • The hostname of all the POM servers across all the Data Centers should be unique.

  • When you add POM servers using the Add POM Server option:
    • If the POM server entries are available on the POM server page, verify the POM server entries in the pim_server table of the POM database.

    • If the POM server entries are present in the pim_server table for the corresponding added POM server, you can skip the addition of the POM server on the Add POM Server page.

    • If you still see the POM server entries on the POM Server page despite corresponding POM server entries are unavailable in the pim_server table, you need to delete the POM server entries from the page and again add the POM server from the Add POM Server page.

  • Always use an active Geo-redundancy server for making REST requests.

Dedicated Experience Portal Zones for POM

Ensure that you provide dedicated zones for POM on the active as well as standby Experience Portal. This simplifies the management of resources substantially in case of running multiple applications on Experience Portal.

Stop processes

Before you add a Data Center using the Add Data Center option, ensure to stop all the POM processes on all the POM servers of all the active and standby Data Centers.