replication
termcloudnetworking
Keeping copies of data on more than one machine, so the loss of one does not lose the data.
The whole subject is the word 'when'. Synchronous replication confirms a write only after the copy has it, which costs latency proportional to distance and guarantees no loss; asynchronous confirms immediately and accepts that a failure loses whatever had not shipped. That choice is the recovery point objective expressed in engineering, and it cannot be avoided - a system that has not chosen has chosen asynchronous by default.
Also known as: mirroring