Today's SAN architectures promise unmediated host access to storage (i.e., without going through a server). To achieve this promise, however, we must address several issues and opportunities raised by SANs, including security, scalability and management. Object storage, such as introduced by the NASD work [14], is a means of addressing these issues and opportunities. An object store raises the level of abstraction presented by a storage control unit from an array of 512 byte blocks to a collection of objects. The object store provides "fine-grain," object-level security, improved scalability by localizing space management, and improved management by allowing end-to-end management of semantically meaningful entities. This paper presents a detailed description of how an object store works and describes the design of Antara, our prototype object store. For a cache hit workload, our pure software prototype is able to service roughly 14000 4K I/O requests per second. We also present a layered security model for an object store which separates concerns of access security and network security, leveraging existing security infrastructure.

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The advances in storage and communications enable users to store massive amounts of data, and to share it seamlessly with their peers. With the advent of XML, we expect a significant portion of this data to be in XML format. We describe here the architecture and implementation of an XML repository that promotes a novel navigation paradigm for XML documents based on content and context. Support for these capabilities is achieved by bringing to bear the organizational power of information retrieval to the domain of semistructured documents. File systems remain the preferred storage infrastructure for the home and business desktop environments. We have built a system, XMLFS, based on the ideas stated above. XMLFS presents a storage abstraction that manifests itself to the client as a familiar file system. However, it breaks the tight coupling between the directory hierarchical structure and the file system. XMLFS creates automatically a directory organization of any XML document collection based on content and context. Each user can navigate through the file system according to her/his domain of interest at that point in time. Our result is a first step towards a solution to the discovery and navigation problems presented by the collective repositories of XML documents in peer-to-peer environments.

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