Beyond Disk Imaging for Preserving User State in Network Testbeds

Many network testbeds today allow users to create their own disk images as a way of saving experimental state between allocations. We examine the effect of this practice on testbed operations. We find that disk imaging is very popular among both research and class users. Excessive disk image creation makes OS upgrades and patches time-demanding, leading over time to experiments that use old and vulnerable images. Since older images are not supported on new testbed hardware this hurts users by reducing their chance of successful resource allocation. Finally, disk images are usually large requiring excessive storage space on testbeds.

We then propose and evaluate three alternatives to disk imaging. We find that each approach significantly reduces storage requirements, and produces a list of OS image customizations that may help testbed users upgrade their images to newer OS versions. While this would still be a very manual process, we believe our results show promise and identify need for further research in this area.