Control system availability for the spallation neutron source ∗

The Spallation Neutron Source (SNS) is continuing its ramp up of beam power, while simultaneously increasing production hours and striving for reduced unplanned downtime. For the large, highly-distributed EPICS-based control system of the SNS, this demand for increased availability is combined with the need for ongoing system maintenance, upgrades and improvements. Causes of recent control system related downtime will be reviewed along with experiences in addressing the competing needs of availability and system improvements.