4,191 research outputs found
Simplified Distributed Programming with Micro Objects
Developing large-scale distributed applications can be a daunting task.
object-based environments have attempted to alleviate problems by providing
distributed objects that look like local objects. We advocate that this
approach has actually only made matters worse, as the developer needs to be
aware of many intricate internal details in order to adequately handle partial
failures. The result is an increase of application complexity. We present an
alternative in which distribution transparency is lessened in favor of clearer
semantics. In particular, we argue that a developer should always be offered
the unambiguous semantics of local objects, and that distribution comes from
copying those objects to where they are needed. We claim that it is often
sufficient to provide only small, immutable objects, along with facilities to
group objects into clusters.Comment: In Proceedings FOCLASA 2010, arXiv:1007.499
Datacenter Traffic Control: Understanding Techniques and Trade-offs
Datacenters provide cost-effective and flexible access to scalable compute
and storage resources necessary for today's cloud computing needs. A typical
datacenter is made up of thousands of servers connected with a large network
and usually managed by one operator. To provide quality access to the variety
of applications and services hosted on datacenters and maximize performance, it
deems necessary to use datacenter networks effectively and efficiently.
Datacenter traffic is often a mix of several classes with different priorities
and requirements. This includes user-generated interactive traffic, traffic
with deadlines, and long-running traffic. To this end, custom transport
protocols and traffic management techniques have been developed to improve
datacenter network performance.
In this tutorial paper, we review the general architecture of datacenter
networks, various topologies proposed for them, their traffic properties,
general traffic control challenges in datacenters and general traffic control
objectives. The purpose of this paper is to bring out the important
characteristics of traffic control in datacenters and not to survey all
existing solutions (as it is virtually impossible due to massive body of
existing research). We hope to provide readers with a wide range of options and
factors while considering a variety of traffic control mechanisms. We discuss
various characteristics of datacenter traffic control including management
schemes, transmission control, traffic shaping, prioritization, load balancing,
multipathing, and traffic scheduling. Next, we point to several open challenges
as well as new and interesting networking paradigms. At the end of this paper,
we briefly review inter-datacenter networks that connect geographically
dispersed datacenters which have been receiving increasing attention recently
and pose interesting and novel research problems.Comment: Accepted for Publication in IEEE Communications Surveys and Tutorial
A Literature Survey of Cooperative Caching in Content Distribution Networks
Content distribution networks (CDNs) which serve to deliver web objects
(e.g., documents, applications, music and video, etc.) have seen tremendous
growth since its emergence. To minimize the retrieving delay experienced by a
user with a request for a web object, caching strategies are often applied -
contents are replicated at edges of the network which is closer to the user
such that the network distance between the user and the object is reduced. In
this literature survey, evolution of caching is studied. A recent research
paper [15] in the field of large-scale caching for CDN was chosen to be the
anchor paper which serves as a guide to the topic. Research studies after and
relevant to the anchor paper are also analyzed to better evaluate the
statements and results of the anchor paper and more importantly, to obtain an
unbiased view of the large scale collaborate caching systems as a whole.Comment: 5 pages, 5 figure
Application of Linear Programming in Scheduling
Distributed computing virtually combines the scattered interconnected computing resources and satisfies the demand of compute-bound and data-hungry applications. The paper highlights various Distributed Computing Environments (DCE), scheduling techniques and need of incorporation of Dynamic Load Balancing (DLB) in scheduling. The paper also opens a new area of research by introducing Linear Programming as a scheduling technique in DCE
Improving OpenStack Swift interaction with the I/O stack to enable software defined storage
This paper analyses how OpenStack Swift, a distributed object storage service for a globally used middleware, interacts with the I/O subsystem through the Operating System. This interaction, which seems organised and clean on the middleware side, becomes disordered on the device side when using mechanical disk drives, due to the way threads are used internally to request data. We will show that only modifying the Swift threading model we achieve an 18% mean improvement in performance with objects larger than 512 KiB and obtain a similar performance with smaller objects. Compared to the original scenario, the performance obtained on both scenarios is obtained in a fair way: the bandwidth is shared equally between concurrently accessed objects. Moreover, this threading model allows us to apply techniques for Software Defined Storage (SDS). We show an implementation of a Bandwidth Differentiation technique that can control each data stream and that guarantees a high utilization of the device.The research leading to these results has received funding from the European
Community under the IOStack (H2020-ICT-2014-7-1) project, by the Spanish
Ministry of Economy and Competitiveness under the TIN2015-65316-P grant and
by the Catalan Government under the 2014-SGR-1051 grant. To learn more about
the IOStack H2020 project, please visit http:nnwww.iostack.eu.Peer ReviewedPostprint (author's final draft
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