What is cold server?
A cold server is a disaster recovery backup server that runs only when the main server is down or fails. A cold server contains all of the main server's files and programs and remains in an unpowered state until a backup is required.
Once the appropriate software is installed on a cold server, it will be disabled until it is needed. Because warm and hot servers are too expensive, cold servers are preferred by most organizations. However, manual configuration of cold server downtime is not always possible, and a cold server requires significant effort to bring it online. Still, this option is significantly cheaper compared to warm and hot servers. In most cases, cold servers contain low-level applications with minimal criticality.