What is Warm Standby Mode?
In the Warm Standby mode, there are only two data centers. The primary data center is up and running, whereas the standby data center is turned on only when the primary data center goes down. The standby data center is regularly backed up with primary data center's data. At times, the data is not mirrored or identical between the two data centers. On failure of the primary data center, the standby data center replaces the primary data center. As part of disaster recovery procedure:
Run the scripts for backup and restore.
Reconfigure the load balancer to redirect the traffic to the standby data center.
Warm standby mode is cost-effective in terms of data center operations. However, the application availability might defer depending on how quickly the standby data center replaces the primary data center. The RPO and RTO for warm standby mode is less when compared to cold standby mode.
Note:
Generally, the standby data center in the warm standby mode is a standalone system. In case of disaster, the standby data center, in the warm standby mode, replaces the primary data center. After the problem is resolved, you must bring the primary data center back into action.