Improving Virtual Appliances through Virtual Layered File Systems

The problem of managing computers is growing in complexity due to the increasing amount of physical and virtual computers that one has to administer as well as the varying roles that those computers fill. As each machine is effectively fully independent, the amount of work an administrator does scales linearly with the amount of machines. In order to solve this problem, we introduce Strata, a system that enables new ways of managing these many distinct installations. Strata enables many systems to be easily managed by introducing a virtual layered file system that composes individual software layers together into a single file system view. By providing the ability to share layers between installations, Strata eases the creation of independent systems and opens up new ways to use computers. We have implemented Strata on Linux without requiring any application or operating system kernel changes. Our measurements on real world applications demonstrate that Strata imposes little overhead