What Does Synchronous Replication Mean?

Synchronous replication is a process for simultaneous updates of multiple repositories often used with a storage area network or wireless network or other segmented system. In synchronous replication, the technology is writing data to two systems at once, rather than one at a time.

Techopedia Explains Synchronous Replication

The idea of synchronous replication is an example of key redundancies used to make systems efficient. Having data available in redundant zones makes that data more resilient if anything were to happen to the system.