BNL, Upton, Long Island, New York, USA
Upgrading hundreds of machines to the next major release of an Operating system (OS), while keeping the accelerator complex running, presents a considerable challenge. Even before addressing the challenges that an upgrade represents, there are critical questions that must be answered. Why should an upgrade be considered? (An upgrade is labor intensive and includes potential risks due to defective software.) When is it appropriate to make incremental upgrades to the OS? (Incremental upgrades can also be labor intensive and include similar risks.) When is the best time to perform an upgrade? (An upgrade can be disruptive.) Should all machines be upgraded to the same version at the same time? (At times this may not be possible, and there may not be a need to upgrade certain machines.) Should the compiler be upgraded at the same time? (A compiler upgrade can also introduce risks at the software application level.) This paper examines our answers to these questions, describes how upgrades to the Red Hat Linux OS are implemented by the Controls group at RHIC, and describes our experiences.
