Cloud

C loud Computing

Virtual Infrastructure
Management in Private
and Hybrid Clouds
One of the many definitions of “cloud” is that of an infrastructure-as-a-service
(IaaS) system, in which IT infrastructure is deployed in a provider’s data center
as virtual machines. With IaaS clouds’ growing popularity, tools and technologies
are emerging that can transform an organization’s existinginfrastructure into a
private or hybrid cloud. OpenNebula is an open source, virtual infrastructure
manager that deploys virtualized services on both a local pool of resources and
external IaaS clouds. Haizea, a resource lease manager, can act as a scheduling
back end for OpenNebula, providing features not found in other cloud software
or virtualization-based data center management software.Borja Sotomayor
University of Chicago
Rubén S. Montero
and Ignacio M. Llorente
Universidad Complutense
de Madrid
Ian Foster
Argonne National Laboratory,
University of Chicago

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Published by the IEEE Computer Society

C

loud computing is, to use a cloudinspired pun, a nebulously defined
term. However, it was arguably
fi rst popularized in 2006 by Amazon’s
Elastic Compute Cloud(EC2; www.
a mazon.com/ec2/), which started offering virtual machines (VMs) for US$0.10
a n hour using both a simple Web interface and a programmer-friendly API.
A lthough not the first to propose a
utility computing model, Amazon EC2
contributed to popularizing the infrastructure-as-a-service (IaaS) paradigm,
which became closely tied to the notion of cloud computing. An IaaS cloud
enableson-demand provisioning of
computational resources in the form
of VMs deployed in a cloud provider’s
data center (such as Amazon’s), mini1089-7801/09/$26.00 © 2009 IEEE

mizing or even eliminating associated
capital costs for cloud consumers and
letting those consumers add or remove
capacity from their IT infrastructure
to meet peak or fluctuating service demands while paying only for theactual
capacity used.
Over time, an ecosystem of providers, users, and technologies has coalesced around this IaaS cloud model.
More IaaS cloud providers, such as
GoGrid, FlexiScale, and ElasticHosts,
have emerged, and a growing number
of companies base their IT strategy on
cloud-based resources, spending little
or no capital to manage their own IT
i nfrastructures (see http://aws.amazon.com/solutions/case-studies/ for several
e xamples). Some providers, such as
IEEE INTERNET COMPUTING

Virtual Infrastructure Management

Elastra and Rightscale, focus on deploying and
managing services on top of IaaS clouds, including Web and database servers that benefit
f rom such clouds’ elastic capacity, and let their
clients provision services directly instead of
having toprovision and set up the infrastructure themselves. Other providers offer products
t hat facilitate working with IaaS clouds, such as
rPath’s rBuilder (www.rpath.org), which enables
u sers to dynamically create software environments to run on a cloud.
Although this ecosystem has evolved around
public clouds — commercial cloud providers
t hat offer a publicly accessible remote interface for creatingand managing VM instances
w ithin their proprietary infrastructure — interest is growing in open source cloud computing tools that let organizations build their own
IaaS clouds using their internal infrastructures.
T hese private cloud deployments’ primary aim
isn’t to sell capacity over the Internet through
publicly accessible interfaces but to give local
u sers a flexible and agileprivate infrastructure
to run service workloads within their administrative domains. Private clouds can also support
a hybrid cloud model by supplementing local infrastructure with computing capacity from an
e xternal public cloud. Private and hybrid clouds
a ren’t exclusive with being public clouds; a private/hybrid cloud can allow remote access to its
resources over the Internet using remote...