Scaling OS Streaming through Minimizing Cache Redundancy

Abstract

OS Streaming is a common data center technique for deploying an OS image quickly onto a physical or virtual machine in which the machine requests the individual blocks of the image from a server as it needs them. When streaming images the server's OS level block cache brings very little in terms of performance as the collection of images is usually too large to fit in memory. We investigate how to improve the scalability of streaming servers by ensuring that blocks {\it shared} among multiple streamed images are preferentially retained in a deduplicated cache. We outline the nature of our deduplicating block cache, describing how cacheable blocks are identified during an off line deduplication process and how an extended form of the Least Recently Used (LRU) block replacement algorithm can be used within the server cache.