Information Technology Reference
In-Depth Information
allows a virtual system to be temporarily associated with physical resources,
and this association can change, decoupling software from the underlying
resources. The current virtualization platform [9] provides a few predei ned
VM images. These VM images are statically coni gured with basic function-
alities. As such, users can either use individual basic VMs and then coni g-
ure them manually, or customize and port their applications to the virtual
environment provided. In some cases, they need to do both. Coni gurations
need to be versatile. This is because some applications are designed for
specii c system architectures, some demand customized coni guration and
administration policies, some run on a VE composed of different VMs, and
some need to be deployed on different virtual platforms. Additionally, VMs
and their connecting VN channels may have their own coni guration
requirements. One or several predei ned VMs are insufi cient to fuli ll all
applications' requirements in a parallel and distributed environment. In a
large-scale distributed computing environment, such as Grid environment,
resources are heterogeneous and their availability varies with time. To adapt
to the dynamics, a VM needs to be dynamically initiated and swiftly
deployed to various heterogonous platforms. To do so, a VM needs to be
reconi gured and migrated from time to time to adapt the resource availabil-
ity. A runtime system is needed to support the reconi guration, redeploy-
ment, migration, and adaptation automatically. This is the same for massively
parallel modern high-end computers, especially for the demands of swift
deployment and fault tolerance. An effective method to model virtual envi-
ronments, manage virtual coni guration, and facilitate fast instantiation and
migration of VMs is necessary. The major technical challenge of providing a
coni gurable and manageable virtual computing environment can be sum-
marized into the search of answers to the following four questions: i rst, how
can we model a virtual environment? Each virtual environment needs to be
coni gured for its target applications. However, common users usually may
not have such knowledge, expertise, and/or time to create and coni gure
their computing environments. Virtual environment modeling is thus a
necessity to achieve automatic coni guration management. Secondly, how
can we instantiate and deploy a virtual environment efi ciently? Since a VM
image could be huge, moving a naive copy of the image to the targeted loca-
tion will deteriorate the performance and overburden the network and stor-
age. Thirdly, how can we support mobility and dynamic management of
virtual environments? Mobility requires efi cient migration and adaptation
to the destination environment, which may be subjected to further security
policy as well as physical constraints. In short, a virtual environment needs
to have the ability to adapt the dynamics of the underlying physical environ-
ment, where the dynamics may be due to the dynamics of the cyberspace or
the accumulated failure rate of massive parallel computers. Finally, how can
we migrate an active VM in a concurrent and coordinated environment?
Migrating and redeploying a VM in a parallel and distributed environment
require the direction and redirection of VM communications during and
Search WWH ::
Custom Search