Packages

Given that software is often distributed as packages, and managed by package management systems, such as the Redhat Package Manager, a natural approach is to leverage these systems to manage software updates and rollbacks. Our upgrade procedure might be as follows: shut down the service, copy system configuration files, upgrade the software (taking care to log the prior version of the upgraded software), and then restart the service. The rollback procedure would be to shut down the service, remove the upgraded software, reinstall prior versions, restore configuration files, and then restart the service.

This approach well achieves the first and second goals of Section 2.2. Depending on the number of packages involved in an upgrade, and the complexity of their installation scripts, however, the corresponding rollback operation may take some time to complete. Thus the approach may not achieve the third goal.