A backup server stands for data backup and availability. Backup servers are used for redundancy and only become active under certain conditions, depending on the backup concept.
Backup servers are components of failover clusters that operate on standby and only become active if the main server fails or if updates have to be performed periodically or regularly. In the first case, one speaks of a cold backup server. Such a cold backup server turns on only when software needs to be installed or configured, or when the actual server fails. On the other hand, a warm backup server turns on regularly to update the software with updates. Such servers are used for replication and mirroring ofdata. The third group of servers are the hot backup servers, which regularly receive updates and operate in hot standby, i.e. they always run in parallel and can directly take over the function of the actual server in the event of a failure.