49 lines
2.5 KiB
Markdown
49 lines
2.5 KiB
Markdown
# Terracotta: A Framework for Dynamic Consolidation of Resources in Openstack Clouds
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Terracotta is an extension to OpenStack implementing dynamic consolidation
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of resources, e.g. Virtual Machines (VMs) using live migration.
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Currently, the major objective is dynamic VM consolidation to improve the utilization
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of physical resources and reduce energy consumption by re-allocating resources using
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live migration according to their real-time resource demand and switching idle hosts to
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the sleep mode.
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For example, assume that two VMs are placed on two different hosts, but the
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combined resource capacity required by the VMs to serve the current load can be
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provided by just one of the hosts. Then, one of the VMs can be migrated to the
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host serving the other VM, and the idle host can be switched to a low power mode
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to save energy. When the resource demand of either of the VMs increases, they
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get deconsolidated to avoid performance degradation. This process is dynamically
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managed by Terracotta.
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In general, the problem of dynamic VM consolidation can be split into 4
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sub-problems:
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- Deciding when a host is considered to be underloaded, so that all the VMs
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should be migrated from it, and the host should be switched to a low power
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mode, such as the sleep mode.
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- Deciding when a host is considered to be overloaded, so that some VMs should
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be migrated from the host to other hosts to avoid performance degradation.
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- Selecting VMs to migrate from an overloaded host out of the full set of the
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VMs currently served by the host.
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- Placing VMs selected for migration to other active or re-activated hosts.
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The aim of the Terracotta project is to provide an extensible framework for
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dynamic consolidation of resources based on the OpenStack platform. The framework
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provides an infrastructure enabling the interaction of components implementing
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the 4 decision-making algorithms listed above. The framework allows
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configuration-driven switching of different implementations of the
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decision-making algorithms.
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## More details
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The Terracotta project idea originally comes from the
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[paper](http://beloglazov.info/papers/2014-ccpe-openstack-neat.pdf) describing
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the architecture and implementation of OpenStack Neat and Chapter 6 of Anton
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Beloglazov's PhD thesis: http://beloglazov.info/thesis.pdf. After discussion with
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the author, we are authorized to use Neat as the Terracotta code base at the very
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early stage. However, a lot of work need to be done according to OpenStack project's
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requirement.
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