Implementing a parallel world model using Linux containers for efficient system administration

This paper describes the implementation of a parallel world model using Linux containers. A parallel world (or parallel universe) model allows a user to create multiple execution environments, called worlds, in a single operating system and to manipulate these worlds. This model enables a system administrator to create a new test world that looks like a production world. The system administrator upgrades fundamental software and tests applications in the new test world while running the production world. If the applications do not pass the tests, the administrator deletes the new world. If the applications pass the tests, the administrator merges the test world into the production world. Prior to the merge, the administrator can examine the differences between these two worlds, and identify any unintentional file modifications. The parallel world model has been implemented using Linux containers and Aufs, a union filesystem. In addition, this implementation uses Auditd, an audit tool, to trace file accesses in worlds. This paper describes the effectiveness of the parallel world model by analyzing a software upgrade process. Experimental results show that the world-related operations are completed within a few seconds, and that it is difficult for remote users to notice the overhead caused by running in parallel worlds.