Hot cloning is a cloning method that takes place while the server OS is running. For virtual machines (VMs), the physical server stays online while the virtual disk image is created from the physical workload and uploaded on the virtual server.
Databases can also be hot cloned while the server is running, but requires a database recovery from the backup files and archive logs. Because the server is active during hot cloning there is no disruption in the workflow. This often makes it the more attractive option over the alternative, cold cloning.
However, with hot cloning there is also a higher risk of data loss. Hot cloning involves taking a snapshot at the beginning of the transition, then copying it to the new VM. Files that are open during the snapshot may not be copied, nor will any changes made after the snapshot. This results in some inconsistencies between the two copies.
Hot cloning is particularly useful for troubleshooting a mission-critical VM without taking it offline. With hot cloning you can make a clone, diagnose the problem on the clone and then apply the solution to the VM.