Internet-like Environment Research Articles

Is cloud storage ready? Performance comparison of representative IP-based storage systems

Network based storage systems have traditionally been dominated by Network Attached Storage (NAS) and Storage Area Network (SAN). Cloud based storage systems, including object storage, have gained growing popularity among both private and enterprise users in recent years. Certain enterprises have even considered replacing traditional storage systems with cloud-based systems. Nevertheless, there still lacks a systematic comparative study on the performance of the aforementioned systems to assist such a transition. To fill in this gap, in this paper, we conduct a comprehensive study on the three major network storage systems with realistic network conditions and application behaviours. Specifically, we select one representative from each category for comparison, i.e., Network File System (NFS) from NAS, Internet Small Computer System Interface (iSCSI) from SAN, and OpenStack Swift from cloud storage. As the first study of its kind, we mainly focus on the client-side and take performance as the perspective for comparison. We build a testbed and a suite of micro-benchmarks to study the impact of network complexities and access behaviours on performance. In addition, we employ two widely used macro-benchmarks – PostMark and FileBench – to test the three systems under realistic workloads. Through a set of comprehensive experiments and thorough analysis, we make several key observations. (1) iSCSI excels under good network conditions, e.g., in local area networks (LANs); when network complexities like network delay and packet loss exist, its performance degrades significantly, especially for data-intensive operations. (2) For Internet-like environments, NFS performs poorly, while Swift demonstrates much resilience. (3) Overall, Swift is a viable replacement for NFS in all network scenarios, while it is not ready yet to replace iSCSI for performance-critical environments. (4) System configuration on the client side impacts storage performance significantly and deserves adequate attention. Based on our experimental study, we also make several recommendations to practitioners and pinpoint aspects for system designers to improve each storage system further.

ConTest: A GUI-Based Tool to Manage Internet-Scale Experiments over PlanetLab

PlanetLab is being used extensively to conduct experiments, implement and study large number of applications and protocols in Internet-like environment. With this increase in PlanetLab usage, there is a pressing need to have efficient way to setup and mange experiments. This paper proposes a graphical user interface-based tool, called ConTest, to setup and mange experiments over PlanetLab. ConTest enables PlanetLab users to setup experiment and collect results in a transparent and easy way. This tool also allows different measurements for different variables over the PlanetLab network. The paper discusses the design and implementation of ConTes and shows different scenarios.

On selfish routing in Internet-like environments

A recent trend in routing research is to avoid inefficiencies in network-level routing by allowing hosts to either choose routes themselves (e.g., source routing) or use overlay routing networks (e.g., Detour or RON). Such approaches result in selfish routing, because routing decisions are no longer based on system-wide criteria but are instead designed to optimize host-based or overlay-based metrics. A series of theoretical results showing that selfish routing can result in suboptimal system behavior have cast doubts on this approach. In this paper, we use a game-theoretic approach to investigate the performance of selfish routing in Internet-like environments based on realistic topologies and traffic demands in our simulations. We show that in contrast to theoretical worst cases, selfish routing achieves close to optimal average latency in such environments. However, such performance benefits come at the expense of significantly increased congestion on certain links. Moreover, the adaptive nature of selfish overlays can significantly reduce the effectiveness of traffic engineering by making network traffic less predictable.

Scalability and accuracy in a large-scale network emulator

This paper presents ModelNet, a scalable Internet emulation environment that enables researchers to deploy unmodified software prototypes in a configurable Internet-like environment and subject them to faults and varying network conditions. Edge nodes running user-specified OS and application software are configured to route their packets through a set of ModelNet core nodes, which cooperate to subject the traffic to the bandwidth, congestion constraints, latency, and loss profile of a target network topology.This paper describes and evaluates the ModelNet architecture and its implementation, including novel techniques to balance emulation accuracy against scalability. The current ModelNet prototype is able to accurately subject thousands of instances of a distrbuted application to Internet-like conditions with gigabits of bisection bandwidth. Experiments with several large-scale distributed services demonstrate the generality and effectiveness of the infrastructure.

A novel loss indication filtering approach for multicast congestion control

A key issue in the design of source-based multicast congestion control schemes is how to aggregate loss indications from multiple receivers into a single rate control decision at the source. Such aggregation entails filtering out a portion of the loss indications received by the source, and then using the remaining for rate adjustments. In this paper, we first propose a set of goals guiding the design of loss indication filters. We then present a novel loss indication filtering approach, the linear proportional response (LPR) approach. Analysis and simulation is used to compare LPR to two well-known approaches — the random listening algorithm (RLA) [Proceedings of ACM SIGCOMM (1998)] and the worst estimate-based tracking (WET) [Proceedings of IEEE Infocom (1999)] approach. Our results indicate that LPR achieves a desirable tradeoff between stability and response, thereby making it more suitable than WET and RLA for deployment in an Internet-like environment.

Alternative specification and verification of a periodic state exchange protocol

The formal analysis of a data-transfer protocol based on the novel idea of periodic state exchange has been presented by Gouda et al. (see IEEE Trans. Commun., vol.43, no.9, p.2475-84, 1995). In certain environments, such as the Internet, the requirements for the correctness of the protocol may impose impractical constraints. We present an alternative specification of the periodic state-exchange protocol based on the discovery that the protocol can be treated as a special sliding-window protocol. Although our protocol behaves better in an Internet-like environment it has other shortcomings with respect to the original. The comparison of the alternatives reveals the trade-offs in their design.