What is a characteristic of the synchronous in-memory system replication mode in SAP HANA?

In the synchronous in-memory system replication mode of SAP HANA, a key characteristic is that the primary system waits for a confirmation from the secondary system before it proceeds with any changes. This ensures that the data is not only written to the primary system's memory but also safely replicated to the secondary system, which is crucial for maintaining data integrity and consistency.

When an update occurs, the primary system sends the data changes to the secondary system and waits for an acknowledgement that the secondary has successfully received and stored the information before committing the transaction on the primary side. This process is fundamental in environments where high availability and data durability are critical, as it minimizes the risk of data loss during failover scenarios.

In contrast, other modes of replication may not require such an acknowledgment, allowing the primary system to operate more independently but potentially at the cost of data reliability.