Abstract
Storage technology trends are providing massive storage in extremely small packages while declining computing costs are resulting in a rising number of devices per person. The confluence of these trends are presenting a new, critical challenge to storage and file system designers: how to enable users to effectively manage, use, and share huge amounts of data stored across a multitude of devices. In this paper, we present a novel middleware storage system, PlanetP, which is designed from first principles as a peer-to-peer (P2P), semantically indexed storage layer. PlanetP makes two novel design choices to meet the above challenge. First, PlanetP concentrates on content-based querying for information retrieval and assumes that the unit of storage is a snippet of XML, allowing it to index arbitrary data for search and retrieval, regardless of the applications used to create and manipulate the data. Second, PlanetP adopts a P2P approach, avoiding centralization of storage and indexing. This makes PlanetP particularly suitable for information sharing among ad hoc groups of users, each of which may have to manage data distributed across multiple devices. PlanetP is targeted for groups of up to 1000 users; results from studying communities of 100-200 peers running on a cluster of PCs indicates that PlanetP should scale well to the 1000-member threshold. Finally, we describe BreezeFS, a semantic file system that we have implemented to validate PlanetP’s utility.