File System Virtual Appliances: Third-party File System Implementations without the Pain (CMU-PDL-08-106)

File system virtual appliances (FSVAs) address a major headache faced by third-party FS developers: OS version compatibility. By packaging their FS implementation in a VM, separate from the VM that runs user applications, they can avoid the need to provide an FS port for every kernel version and OS distribution. A small FS-agnostic proxy, maintained by the core OS developers, connects the FSVA to whatever kernel version the user chooses. Evaluation of prototype FSVA support in Linux, using Xen as the VM platform, demonstrates that this separation can be efficient and maintain desired OS and virtualization features. Using three existing file systems and a cooperative caching extension as a case study, we demonstrate that the FSVA architecture can insulate FS implementations from user OS differences that would otherwise require explicit porting changes. Acknowledgements: We thank the members and companies of the CyLab Corporate Partners and the PDL Consortium (including APC, Cisco, EMC, Google, Hewlett-Packard, Hitachi, IBM, Intel, LSI, Microsoft, Network Appliance, Oracle, Seagate, Symantec, and VMware) for their interest, insights, feedback, and support. This material is based on research sponsored in part by the National Science Foundation, via grants CNS-0326453 and CCF-0621499, by the Department of Energy, under Award Number DE-FC02-06ER25767, and by the Army Research Office, under agreement number DAAD19–02–1–0389. Matthew Wachs was supported in part by an NDSEG Fellowship, which is sponsored by the Department of Defense. We thank Intel and Network Appliance for hardware donations that enabled this work.