Since migrating to Windows Server 2008 Datacenter for our Amazon EC2 instances I have noticed on many occasions that when a new instance is starting up RAC agent will cause the CPU to spike up to 100% for a good half an hour, at times the CPU spike never comes down and effectively renders the instance unusable..
After some digging around, I found this article which tells you how to disable the RAC agent:
In case the link stops working in the future, here’s the 4 steps you need to do:
1. go to Control Panel –> Administrative Tools –> Computer Management
2. navigate to System Tools –> Task Scheduler –> Task Scheduler Library –> Microsoft –> Windows –> RAC
3. right click RAC, select View –> Show Hidden Tasks
4. right click on the displayed task, and select Disable