Brighten Godfrey

Learn More
Distributed storage systems provide reliable access to data through redundancy spread over individually unreliable nodes. Application scenarios include data centers, peer-to-peer storage systems, and storage in wireless networks. Storing data using an erasure code, in fragments spread across nodes, requires less redundancy than simple replication for the(More)
Networks are complex and prone to bugs. Existing tools that check configuration files and data-plane state operate offline at timescales of seconds to hours, and cannot detect or prevent bugs as they arise. Is it possible to <i>check network-wide invariants in real time</i>, as the network state evolves? The key challenge here is to achieve extremely low(More)
Data centers today form the backbone of cloud operations. A well provisioned data center network is important to ensure that servers do not face bandwidth bottlenecks to utilization; to isolate services from each other; and to gain more freedom in workload placement, rather than having to tailor placement of workloads to where bandwidth is available [16].(More)
Most P2P systems that provide a DHT abstraction distribute objects randomly among “peer nodes” in a way that results in some nodes having times as many objects as the average node. Further imbalance may result due to nonuniform distribution of objects in the identifier space and a high degree of heterogeneity in object loads and node capacities.(More)
Diagnosing problems in networks is a time-consuming and error-prone process. Existing tools to assist operators primarily focus on analyzing control plane configuration. Configuration analysis is limited in that it cannot find bugs in router software, and is harder to generalize across protocols since it must model complex configuration languages and(More)
A pervasive requirement of distributed systems is to deal with churn-change in the set of participating nodes due to joins, graceful leaves, and failures. A high churn rate can increase costs or decrease service quality. This paper studies how to reduce churn by selecting which subset of a set of available nodes to use.First, we provide a comparison of the(More)
We give improved approximation algorithms for a variety of latency minimization problems. In particular, we give a 3.591-approximation to the minimum latency problem, improving on previous algorithms by a multiplicative factor of 2. Our techniques also give similar improvements for related problems like k-traveling repairmen and its multiple depot variant.(More)
Global-scale organizations produce large volumes of data across geographically distributed data centers. Querying and analyzing such data as a whole introduces new research issues at the intersection of networks and databases. Today systems that compute SQL analytics over geographically distributed data operate by pulling all data to a central location.(More)