In Release 4.0A upwards, all availability checking is carried out on a dedicated machine, known as the ATP Server. Many kinds of checks are possible, including:
The ATP Server has a Shared Buffer where the requirements quantities in the database tables RESB (reservations and dependent requirements) and VBBE (sales requirements) are aggregated by date. The Shared Buffer acts as a global memory for all transactions that use availability checking. When checking availability, the system reads the data from these two tables - that is, from the Shared Buffer - rather than from the database. This method has major performance advantages. A delta handling mechanism ensures that the Shared Buffer and the database are consistent with each other.
Another new feature is the ability to check requirements specific to particular customers and projects at storage location and/or batch level. This check functions in the same way as the check for non-specific requirements, which was already available in Release 3.1.
You set the system parameters of the ATP Server at operating system level in the ATP Server profile. These parameters are:
For more information on these parameters, see transactions RZ11 and ST02.
Transaction ACBD offers further monitoring and administrative functions for the Shared Buffer of the ATP Server: e.g.
This transaction also allows you to preload the data from the database into the Shared Buffer. Otherwise, the data is loaded the first time availability is checked - which could take some time.