Mirrored Regions with Different Values

Whenever there are multiple, physically different copies of the same value that might change and the process to update them is not instantaneous and atomic, it is impossible to assert that the original and shadow copies will always be in sync - there will always be a time period when they are out of sync. To mitigate the consequential risk, the recommendations essentially are: Make this out-of-sync time period as small as possible, and Make the update process as robust as possible.