Improving I/O Performance using Virtual Disk Introspection

Storage consolidation due to server virtualization puts stringent new requirements on Storage Array (SA) performance. Virtualized workloads require new performance optimizations that cannot be totally addressed by merely using expensive hardware such as SSDs. This position paper presents Virtual Machine Disk Image (VMDI) introspection—a key technique for implementing a variety of virtualization-oriented I/O optimizations. VMDI introspection gives SAs an understanding of guest file system semantics, such as determining object types and classifying read and write operations. We explore possible approaches for VMDI introspection and then describe a set of VMDI-introspection-based optimizations. Our prototype implementation with enhanced meta-data caching and placement shows 11% to 20× performance improvement.