What is cold standby?
Cold standby is a redundancy method in which one system is used as a backup for another identical primary system. The cold standby system is only called up if the primary system fails.
Cold standby systems turn on once to install and configure the system and data, and then turn off until needed. After that, it is only used when updating non-critical data that is rarely done or when the primary system fails.
In contrast, a hot standby system runs concurrently with another identical primary system. If the primary system fails, the hot standby system immediately takes over the replacement of the primary system. In such a setup, the data is mirrored in real time and both systems have identical data.
A warm standby system, on the other hand, runs in the background of the primary system and the data is regularly mirrored to a secondary server. Therefore, the primary and secondary systems sometimes contain different data or different versions of data.