Antiquity is a wide-area distributed storage system designed to provide a simple storage service for applications like file systems and back-up. The design assumes that all servers eventually fail and attempts to maintain data despite those failures. Antiquity uses a secure log to maintain data integrity, replicates each log on multiple servers for durability, and uses dynamic Byzantine fault-tolerant quorum protocols to ensure consistency among replicas. We present Antiquity's design and an experimental evaluation with global and local testbeds. Antiquity has been running for over two months on 400+ PlanetLab servers storing nearly 20,000 logs totaling more than 84 GB of data. Despite constant server churn, all logs remain durable.

We broaden the applicability of peer-to-peer storage infrastructures to weakly-connected clients. We present a client-side technique that exploits the commonality between consecutive versions of a file to reduce the bandwidth required to store and retrieve files in a peer-to-peer storage infrastructure. We then present a novel data structure that allows us to use this technique in an environment where peers cannot be trusted to perform operations over unencrypted data. We have implemented the technique in the OceanStore prototype. Additionally, with simulations, we have demonstrated that the technique can reduce client-perceived latency of write and read operations by up to 80% compared to techniques used in current systems.

OceanStore is a utility infrastructure designed to span the globe and provide continuous access to persistent information. Since this infrastructure is comprised of untrusted servers, data is protected through redundancy and cryptographic techniques. To improve performance, data is allowed to be cached anywhere, anytime. Additionally, monitoring of usage patterns allows adaptation to regional outages and denial of service attacks; monitoring also enhances performance through pro-active movement of data. A prototype implementation is currently under development.

Explicitly Parallel Instruction Computing (EPIC) architectures require the compiler to express program instruction level parallelism directly to the hardware. EPIC techniques which enable the compiler to represent control speculation, data dependence speculation, and predication have individually been shown to be very effective. However these techniques have not been studied in combination with each other. This paper presents the IMPACT EPIC Architecture to address the issues involved in designing processors based on these EPIC concepts. In particular we focus on new execution and recovery models in which microarchitectural support for predicated execution is also used to enable efficient recovery from exceptions caused by speculatively executed instructions. This paper demonstrates that a coherent framework to integrate the three techniques can be elegantly designed to achieve much better performance than each individual technique could alone provide.