Performing a Failback
Once your original primary system is operational again after a disaster or planned downtime, for example, you can fail back to your original primary system.
Prerequisites
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You have the authorization to perform the operation.
For more information, see Standard Permissions.
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You have assigned the roles and groups required to perform the operation.
For more information, see Standard Roles and Groups.
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You comply with the prerequisites for system replication described in the SAP HANA Administration Guide.
For more information, see SAP Help Portal at https://help.sap.com/viewer/p/SAP_HANA_PLATFORM.
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You are logged on to both systems as the operating system user (user <sid>adm) or are able to enter these credentials when prompted.
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You have performed a data backup on the current primary system.
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The software version of the current secondary has to be equal or newer to the version of the current primary.
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The original primary system is in status
Not Running.
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The current primary system is in status
Running.
Context
To fail back to your original primary system, you must switch the roles of your two systems back to their original configuration.
In this scenario when the new secondary is registered with the new primary it checks if it is possible to do a delta shipping rather than carrying out a full data shipping. If this is possible it only ships the delta which significantly reduces the initialization time.
When the new secondary starts up it checks first if there is a local snapshot available from time when the system was the primary system. If a snapshot is available the system then checks if it is compatible with the new primary. When both checks are positive the new secondary can be initialized with a delta replica from the new primary.



