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How a machine or system can transfer the failed operations to a back up without interupting flow.

Automatically switching to a different,redundant system upon failure or abnormal termination ofthe currently active system. Failover can be applied to acluster of servers, to network or storage components orany other set of redundant devices that must provide highavailability because down-time would be expensive orinconvenient. It may be implemented in hardware, software ora combination.A "hot standby" is continuously active at the same time asthe failed system, using some kind of load balancing toshare the work, whereas a "warm standby" is ready to becomeactive at short notice.When the failed system is operational again it may "failback",i.e. become (one of) the active system(s) or it may become awarm standby.