Reducing Storage Management Costs via Informed User-Based Policies

Erez Zadok, Jeffrey Osborn, Ariye Shater, Charles Wright, Kiran-Kumar Muniswamy-Reddy, Jason Nieh

Dept. of Computer Science, Stony Brook University Technical Report , FSL-03-01, March 2003

Abstract

Storage consumption continues to grow rapidly, espe- cially with the popularity of multimedia files. Worse, current disk technologies are reaching physical me- dia limitations. Storage hardware costs represent a small fraction of overall management costs, which in- clude backups, quota maintenance, and constant inter- ruptions due to upgrades to incrementally larger stor- age. HSM systems can extend storage lifetimes by mi- grating infrequently-used files to less expensive storage. Although HSMs can reduce overall management costs, they also add costs due to additional hardware. Our key approach to reducing total storage manage- ment costs is to reduce actual storage consumption. We achieve this in two ways. First, whereas files often have persistent lifetimes, we classify files into categories of importance, and allow the system to reclaim some space based on a file’s importance (e.g., transparently com- press old files). Second, our system provides a rich set of policies. We allow users to tailor their disk usage poli- cies, offloading some of the management burdens from the system and its administrators. We have implemented the system and evaluated it. Performance overheads un- der normal use are negligible. We report space savings on modern systems ranging from 20% to 75%, which result in extending storage lifetimes by up to 72%.

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Columbia University Department of Computer Science