Query Regarding Synchronous Replication Setup During Tenant Copy

[SAPSupport]

Hi  Team,

We are currently migrating the existing PERSON_NAME DB Servers from Data Center A to Data Center B using the Tenant Copy method.

In the **source environment** (Data Center A), we have 3 nodes: 2 PERSON_NAME DBs (Primary and Secondary without automatic failover) and a DR.  
The **target environment** (Data Center B) also consists of 3 nodes: 2 PERSON_NAME DBs (Primary and Secondary with HA auto-failover using Suse Pacemaker) and a DR.

In both environments, **HSR is enabled**, with synchronous replication from Primary to Secondary and asynchronous replication from Secondary to DR.

As tenant copy is being performed from Data Center A to Data Center B while replication is active in Data Center A, I would like to inquire if it is possible to configure **synchronous replication** from Data Center B's Primary to Secondary during the Tenant Copy process. During the cutover, the target tenant database will operate as an independent database.

The reason for this request is that, with a database size of 15 TB and tight timelines, we want to avoid a single point of failure during the go-live and minimize extended replication times between the Primary and HA nodes. We would appreciate any insights on whether this setup is technically feasible.

Best regards, 

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[SAPSupport · Accepted solution]

Dear customer,

According to your description, it seems like you want to save the time which is supposed to be taken for full replication of the secondary site in DC B after the replica from DC A has been completed.
And, my answer for the scenario is Yes.
You can set up the replication between the primary and secondary in DC B while the tenant copy is being performed.
But, you should take care of a few things.
1) There should not be any events which might affect to the primary site in DC B because of any issue caused by the secondary site in DC B.
Regarding to the possible causes which affect to the primary site, please refer to the section "9. Can problems with system replication impact the performance on the primary system?" in KBA 1999880 - FAQ: SAP HANA System Replication.

2) Stable network status between the primary and secondary in DC B.
Please take a look at KBAs below to make sure the stable connectivity between two sites.
2382421 - Optimizing the Network Configuration on HANA- and OS-Level
2222200 - FAQ: SAP HANA Network (14.What can happen if the maximum transmission unit (MTU) is inconsistently configured?)
1999880 - FAQ: SAP HANA System Replication("8. What are the basic requirements for the SAP HANA system replication network connection regarding throughput and latency?")

3) Please do not register DR to the secondary site in DC B until the tenant copy has been completed.
It could be another burden for the primary site to maintain the asynchronous log buffer for DR site.
So, it is recommended to register DR site after tenant copy is completed.

Best regards,
SAP Support