Multi-layered Virtual Machines for Security Updates in Grid Environments

The use of user specific virtual machines (VMs) in Grid and Cloud computing reduces the administration overhead associated with manually installing required software for every user on every computational resource. However, a large number of user specific VMs increases the risk of security attacks. In particular, Cloud computing providers like Amazon suffer from these problems, since they offer different operating systems within VMs and delegate the security update problem for VMs to the users. In this paper, a solution that solves the problem by separating a VM into several layers is presented. The approach creates the possibility of installing security updates into a base layer centrally, affecting all VMs without affecting the users' own installed software stack by merging package databases. The proposal permits resource providers to keep a large number of VMs patched with the latest security fixes without bothering the users. Furthermore, the proposal avoids the overhead for transferring possible large VM images over the network between the nodes of a Grid or Cloud by allowing to hold locally cached VM images with a basic operating system installation while only the user-specific software stack stored in a separate layer needs to be transferred.