Question: What is resource locking and lock modes?

Answer:

This section discusses the lock modes and the policy of unlocking.

All users are locked including the owner
In this case, no changes are allowed on the resource not even if the owner attempts it. This mode is used when the user does not want any change in the system until a critical situation has passed.

All users except for the owner are locked
In this case, the owner can make the changes, but others cannot. This policy is useful when the user is in the process of making some critical changes, but does not want others to make changes which can interfere with what is being modified. 

These locks are persistent which means that they are applicable even on a system restart and across user sessions. The lock itself can be released by the owner or the ProviderDataCenterAdmin or ProviderDataCenterSystemAdmin users can unlock it. In the Director, the locks are valid only from the perspective of the UI and the rest layer, they are not applicable at the CLI level.