Operating system upgrade in high availability environment

The high availability requirement for services does not allow for more than five minutes of down time per year including downtime scheduled for maintenance and upgrades. The upgrade of applications providing such services is challenging and has to be planned very carefully. The challenge becomes even bigger when it comes to the upgrade of the underlying supporting lower layers, the middleware and the operating system (OS). In this paper, we explore the challenges of OS upgrade and propose solutions built on an existing standard middleware service for software management.