You can replace hardware as needed without interruption to the services
being provided.
Summary
In this chapter we explored two different ways of migrating Xen guest domains:
Save and restore??”A mechanism similar to laptop hibernation where the
running domain state is captured in an image on the disk and is later used
for restoring that domain.
Live Migration??”Live relocation of an active running domain with minimal
disruption and downtime.
In the next chapter, we will look at some future trends in Xen.
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Xen Future
In this chapter we will discuss some of the recent enhancements and ideas based on
Xen. Most of these are still evolving or are fairly new and will likely change over
time. We will discuss the following technologies in this chapter:
Libvirt
VMcasting
Libvirt
Libvirt is a virtualization API for interacting with the various virtualization
implementations (http://libvirt.org/index.html). It is essentially a C API, but
provides bindings for a variety of languages, Python being the best supported. It
is very actively maintained and supported by the open-source community. In its
present form it provides support for accessing Xen virtualization, KVM, and QEMU.
However, it is built to be framework independent and provide support for accessing
other virtual instances as they become available.
In order to provide the decoupling of the virtualization technology from the API,
libvirt defines the following abstract notions of a virtual instance:
Node: A single physical machine.
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