Learn in the textbookSystem Configurations for Availability and Reliability
DefinitionReplication (レプリケーション) is a function, mainly provided by a DBMS (the software that manages a database), that keeps a copy of a database on another server and applies each update made at the source to the copy, keeping the two in sync.
ExplanationBecause the replica holds the same contents as the source, processing can continue on the replica if the source server fails, which raises availability, the degree to which a system stays usable without stopping. Sending read requests to the replica also lightens the load on the source server and improves performance.
AnalogyIt is like a head store whose every entry in the stock ledger is copied into the branch's ledger too. Even when the head store is closed, the branch can answer inquiries from its own ledger.
Memory hookA "replica" is a copy, the same word used for museum reproductions. Think of a function that keeps making copies you cannot tell from the original.