Gregory R. Ganger

Learn More
To better understand the challenges in developing effective cloud-based resource schedulers, we analyze the first publicly available trace data from a sizable multi-purpose cluster. The most notable workload characteristic is heterogeneity: in resource types (e.g., cores:RAM per machine) and their usage (e.g., duration and resources needed). Such(More)
This paper presents a practical solution to a problem facing high-fan-in, high-bandwidth synchronized TCP workloads in datacenter Ethernets---the TCP incast problem. In these networks, receivers can experience a drastic reduction in application throughput when simultaneously requesting data from many servers using TCP. Inbound data overfills small switch(More)
A <i>fault-scalable</i> service can be configured to tolerate increasing numbers of faults without significant decreases in performance. The Query/Update (Q/U) protocol is a new tool that enables construction of fault-scalable Byzantine fault-tolerant services. The optimistic quorum-based nature of the Q/U protocol allows it to provide better throughput and(More)
The exokernel operating system architecture safely gives untrusted software efficient control over hardware and software resources by separating management from protection. This paper describes an exokernel system that allows specialized applications to achieve high performance without sacrificing the performance of unmodified UNIX programs. It evaluates(More)
Disk subsystem performance can be dramatically improved by dynamically ordering, or <italic>scheduling</italic>, pending requests. Via strongly validated simulation, we examine the impact of complex logical-to-physical mappings and large prefetching caches on scheduling effectiveness. Using both synthetic workloads and traces captured from six different(More)
Cluster-based and iSCSI-based storage systems rely on standard TCP/IP-over-Ethernet for client access to data. Unfortunately, when data is striped over multiple networked storage nodes, a client can experience a TCP throughput collapse that results in much lower read bandwidth than should be provided by the available network links. Conceptually, this(More)
Services that share a storage system should realize the same efficiency, within their share of time, as when they have the system to themselves. The Argon storage server explicitly manages its resources to bound the inefficiency arising from inter-service disk and cache interference in traditional systems. The goal is to provide each service with at least a(More)
For decades the RAM-to-disk memory hierarchy gap has plagued computer architects. An exciting new storage technology based on microelectromechanical systems (MEMS) is poised to fill a large portion of this performance gap, significantly reduce system power consumption, and enable many new applications. This paper explores the system-level implications of(More)
Sophisticated disk scheduling algorithms require accurate, detailed disk drive specifications, including data about mechanical delays, on-board caching and prefetching algorithms, command and protocol overheads, and logical-to-physical block mappings. Comprehensive disk models used in storage subsystem design require similar levels of detail. We describe a(More)
This paper describes a decentralized consistency protocol for survivable storage that exploits local data versioning within each storage-node. Such versioning enables the protocol to efficiently provide linearizability and wait-freedom of read and write operations to erasure-coded data in asynchronous environments with Byzantine failures of clients and(More)