Networked storage-systems typically use codes to protect data from failures. In this work we deal with aspects of hierarchical reliability and object-based storage schemes. A hierarchical-reliability scheme maintains devices employing different coding schemes, and transits data between these groups based on activity level. Object-based storage utilizes basic storage-devices storing variable-sized objects, as opposed to blocks. The use of hierarchical object-based storage, requires a policy to transition data between different levels. We discuss such a policy for a two-level system, and show how to extend it for a multiple-level system. We then show an information-theoretic interpretation for the need for hierarchical reliability, and show implications for the necessity of hierarchical reliability schemes as the growth-gap between storage-devices' capacity and IO-bandwidth continues.
By: Ami Tavory, Vladimir Dreizin, Shmuel Gal, Meir Feder
Published in: H-0213 in 2003
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