SAP Transaction Banking: Case Study Understanding Data Sharing Effects as a Function of Long Distance Coupling Links IBM System Z
Data sharing is used to cluster multiple System z servers (CECs) residing either in the same or remote location(s). Data integrity and process coordination for these clusters are ensured and provided through a special server called a Coupling Facility (CF). Each CEC is connected with the CF through the so called coupling links. Light transmission technology is used to transfer the signals across the entire cluster. The advantages of the data sharing technology are available at the expense of moderate performance overheads. The overheads are due to the time required for the light to travel between CEC and CF. The initial data sharing overheads are higher the longer the distance between the CEC and CF.