a case-by-case basis in real time.

Open Issues
===========

Our current implementation of containers uses the default directory backing store, and as a result, each additional layer duplicates the entire filesystem of the previous layer plus the new data. For a layered setup like the one we demonstrated, a more ideal solution would be to try using an overlay filesystem such as overlayFS, which allows the sharing of lower-layer files with different upper layers. This would provide a much more efficient usage of storage, and is much closer to the abstract model. However, LXC currently does not support overlayFS yet (as of version 1.1.5).

Another way of potentially improving performance, especially service downtime, would be to investigate the use of iterative migration. Iterative migration is the process of transferring memory pages whilst the service is running, so that when the service is finally suspended and migrated, in theory, only a small portion of the remaining in-memory state needs to be transferred.

For our experiments, LXC offered the greatest ease for running different applications without specialist knowledge in order to set them up. Other container technologies exist, among them Docker ([www.docker.com](www.docker.com)) which has become the de facto standard for containerization. Future 