Sysplex shared data coherency method

A method of controlling data coherence for a computer multi-system complex, comprising the steps of

• structuring the computer multi-system complex as a sysplex which includes a plurality of central processor complexes (CPCs), sysplex direct access storage devices (DASDs) connected to the CPCs for storing data elements permanently in the sysplex, and a shared electronic storage (SES) attached to the CPCs, command issuers which execute in the CPCs to issue commands to the SES, said SES containing a SES cache with a SES cache directory for storing names of the data elements, the same data element name being used throughout the sysplex to identify all copies of the same data element stored anywhere in the sysplex whether or not any data element copy is changed relative to the data element or any copy of the data element,
• communicating a registration command to the SES by a command issuer in a CPC for providing a data element name and associated CPC location information for locating in the CPC a validation indication associated with a data element copy stored in a local LCB in the CPC, the registration command controlling SES to register the data element copy for the SES cache,
• registering the associated CPC location information in a local cache register (LCR) associated with a SES cache directory entry storing the data element name in the SES cache directory in response to the communicating step, and
• accumulating all CPC location information in the LCR for all registration commands received for the same SES cache entry containing the data element name for locating all validation indicators for all copies of the data element in all connected CPCs in the sysplex for enabling coherence control for the copies of the data element among the CPCs in the sysplex.