Availability of Globally Distributed Nodes: An Empirical Evaluation

Warns, Timo; Storm, Christian; Hasselbring, Wilhelm

doi:10.1109/srds.2008.9

Cited by 9 publications

(6 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This corresponds to the relevant process availability interval for real-life systems [26]. Moreover, one can use poPQS obtained through our approaches for executing 'last minute' still available operations (i.e.…”

Section: Discussionmentioning

confidence: 99%

Relaxing data consistency along different dimensions for increasing operation availabilities

Lipskoch

Theel

2014

International Journal of Parallel, Emergent and Distributed Sys

View full text Add to dashboard Cite

Pessimistic quorum-based data replication strategies have strictly upper-bounded operation availabilities. The probabilistic relaxation of their strict consistency notion along different dimensions permits to overcome this upper-bound. The resulting probabilistic replication strategies allow the exploitation of the data consistency versus operation availabilities trade-off. In our approaches, we add a certain number of probabilistically intersecting quorums to the originally strictly intersecting partially ordered quorum system in order to 'closely conserve' its original characteristic behaviour. As one expects, the number and nature of probabilistic quorums added have a strong impact on the particular trade-off. We present two algorithms for the generation of probabilistic quorums based on input strict quorums. Furthermore, the order in which probabilistic and strict quorums are to be probed and used for executing operations is also very important. We relate three general strategies of ordering the probabilistic and strict quorums of those probabilistic quorum systems (PQSs), evaluate their impact on the data consistency versus operation availabilities trade-off and compare them in terms of this trade-off. The evaluation uses Markov chain-based steady-state analysis applied to a representative instance of PQSs with adequate partial orderings.

show abstract

Section: Discussionmentioning

confidence: 99%

Relaxing data consistency along different dimensions for increasing operation availabilities

Lipskoch

Theel

2014

International Journal of Parallel, Emergent and Distributed Sys

View full text Add to dashboard Cite

show abstract

“…However, it turned out that some of them nevertheless had more or less permanent problems. The overall poor dependability of Planet-Lab nodes as observed by Warns et al in [26] is a general problem that limits the number of available landmarks significantly. Some of the problems we encountered are firewalls blocking MySQL traffic, gateways blocking traffic between the commercial Internet and Internet2 networks.…”

Section: Iii� Topology Generatormentioning

confidence: 99%

Towards Improved Overlay Simulation Using Realistic Topologies

Pfeifer¹,

Spring²,

Fetzer³

2009

2009 Eighth IEEE International Symposium on Network Computing and Applications

View full text Add to dashboard Cite

Simulation of distributed applications and overlay networks is challenging. Often the results generated in simulation do not match experimental results. Distributed testbeds like Planet-Lab help to bridge the gap, but they do not offer enough nodes to do an Internet scale evaluation. In this paper we use a tool called TopDNS for generating realistic topologies for simulations, using the Planet-Lab to collect measurement data. We show, that simulation results may differ significantly from earlier results using synthesized topologies. We provide a data analysis to explain the observed results and to provide a better understanding of latency between hosts in certain DNS name spaces. I� IntroductionIn recent years, peer-to-peer overlay networks have been used to implement applications, that before have been implemented using client-server architecture. Such applications, like group communication [1], web caching [2], [3], block storage [4], and e-mail [5] should benefit from the increased reliability and connectivity of overlay networks.One significant problem has been a correct evaluation of such systems using large scale simulation. Apart from the scalability of the simulator, a network topology must be chosen. For Internet scale systems, this is difficult, because the Internet is a large dynamic network with an unknown, continuously changing topology. Often a selection of known networks and nodes is used to extract certain characteristics, like connectivity, distance distribution, bandwidth distribution, etc. These properties are then scaled up to match the estimated Internet size or the targeted deployment size of the overlay application.During simulations, there are three gaps that limit the validity of the results: (1) the gap between Internet addresses and addresses in abstract topologies, (2) the gap between real workloads and abstract workloads, and (3) the gap between Internet characteristics and community characteristics.The first and second are caused by the common procedure of simulating the application's behavior on the overlay using workloads from earlier client-server implementations. This procedure does not work properly, if the workload contains references to the network topology, e.g., IP addresses, host names, network masks, etc. Hence, an abstraction of these workloads must be produced.The third problem is, that for certain applications, only a very limited group of Internet hosts is important. The statistical network characteristics of this group might be different from the characteristics of the overall Internet. E.g., if an illegal file sharing application for movies shall be simulated, the community of participating nodes might consist of nodes with DSL dial-up connections having good bandwidth but poor responsiveness (high delay, high jitter). None of them would be well connected to the Internet. If one would use an overlay that depends on using nodes with a high fan-out as supernodes (e.g. [6]), this might work well in simulations on a general Internet topology, but in our example, the real...

show abstract

“…The expected value of the eligibility set size is also an indicator of the average number of tasks of a given resource capacity requirement that can be scheduled in the system. In this study we are not concerned with node availability in terms of the MTTF and MTTR of the PlanetLab nodes as presented in [25]. Our focus is on the eligibility periods of nodes for some given resource capacity requirements; these periods typically tend to be much smaller than the MTTF values (mean 3.8 days and median 3.16 days as reported in [25]).…”

Section: Lack Of Guarantees For Node Availabilitymentioning

confidence: 99%

“…The primary goal of our work is to develop node selection techniques for application placement and dynamic relocation and our study of resource availability characteristics was driven by this goal. The work presented in [25] provided characterization of node availability in PlanetLab based on MTTF and MTTR measures. As compared to that work, our focus is on available capacities on node and their eligibility for various requirement levels.…”

Section: Related Workmentioning

confidence: 99%

Resource Availability Characteristicsand Node Selection in CooperativelyShared Computing Platforms

Padhye

Tripathi

2014

IEEE Trans. Parallel Distrib. Syst.

View full text Add to dashboard Cite

Abstract-The focus of our work is on developing techniques for selecting nodes for scheduling applications in large-scale, cooperatively pooled, shared computing platforms. In such platforms, resources at a node are allocated to competing users on fair-share basis, without any reserved resource capacities for any user. There is no platform-wide resource manager for the placement of users on different nodes. The users independently select nodes for their applications. Our study is focused on the PlanetLab environment which exemplifies such platforms. For developing node selection techniques, we first study the resource utilization characteristics of PlanetLab nodes. Our approach uses the notion of eligibility period, which represents a contiguous duration for which a node satisfies a given resource requirement. We study the characteristics of the eligibility periods of Planetlab nodes for various resource capacity requirements. Based on this study we develop models for identifying nodes that are likely to satisfy a given requirement for long durations. We also develop an online model for predicting the idle resource capacity that is likely to be available on a node over a short term. We evaluate and demonstrate the performance benefits of the node selection techniques and the prediction model using the PlanetLab node utilization data traces collected at different intervals over an extended period of several months.

show abstract

Availability of Globally Distributed Nodes: An Empirical Evaluation

Cited by 9 publications

References 8 publications

Relaxing data consistency along different dimensions for increasing operation availabilities

Relaxing data consistency along different dimensions for increasing operation availabilities

Towards Improved Overlay Simulation Using Realistic Topologies

Resource Availability Characteristicsand Node Selection in CooperativelyShared Computing Platforms

Contact Info

Product

Resources

About