Remote replication is the process of copying production data to a device at a remote location for data protection or disaster recovery purposes.
Remote replication may be either synchronous or asynchronous. Synchronous replication writes data to the primary and secondary sites at the same time. With asynchronous replication, there is a delay before the data gets written to the secondary site. Because asynchronous replication is designed to work over longer distances and requires less bandwidth, it is often a better option for disaster recovery. However, asynchronous replication risks a loss of data during a system outage because data at the target device isn't synchronized with the source data.
Replication occurs in one of three places: in the storage array, at the host (server) or in the network. Most enterprise data storage vendors include replication software on their high-end and mid-range storage arrays. Host-based replication software runs on standard servers, making it the cheapest and easiest type of replication to manage for many, but it taxes server processing. Replication on the network requires an additional device, either an intelligent switch or an appliance.
Data can also be replicated remotely to a cloud backup service.
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