What happens in a typical organization when there is catastrophic damage to a hardware component that requires rebuilding form scratch? In many organizations the existing production configuration would not be definitively known and the exact version of software that was installed is often unknown and not locatable. This results in a rebuilt component that differs from the previous production component. Sometimes few or no differences are noticed. Often critical differences in performance or functionality are found. Sometimes they are found immediately and sometimes they are found much after the fact with significant impact to the business.
The more common scenario is a server room with common hardware and no two servers running the same software configuration. Often desktops will be imaged with different images by different technicians because definitive policies and definitive software stores are nonexistent. Although this seems to be a trivial issue it is the cause of many incidents and increases the costs of maintaining services.
The definitive software store is a dedicated location or group of locations where a definitive copy of every version of software in the production environment is stored. It also stores software versions that have been retired. This provides the capability to restore previous environments for any number of situations some of which are as critical and as potentially costly as regulatory compliance issues. The DSL does not stand alone. It requires definitive understanding of current and past environmental configurations. Maintaining this information is part of configuration management and the configuration management database.
A similar concept is that of the definitive hardware store. This is a location that has backup hardware components that allow for immediate replacement when critical components fail.