Operational experience and optimization techniques for large EPICS control system environments

The Spallation Neutron Source (SNS) utilizes the EPICS control system to manage the main accelerator, multiple test stands, and most neutron scattering instruments. The control system environment for the main accelerator alone includes approximately 300 Input/Output Controllers (IOCs), 200 soft IOCs, and 100 Operator Interface (OPI) workstations, all communicating through over 1,000,000 process variables. The EPICS distributed control system relies heavily on UDP broadcast communication to locate process variables on the network, which can significantly impact the operation of connected devices and, in turn, affect accelerator uptime. In this paper, we present operational challenges and discuss optimization techniques applied to the EPICS environment at SNS.