Virtualization as High Availability (Disaster Recovery) or High-Availability as Virtualization?
Many pundits and other folks like VMware’s CEO Diane Greene have touted virtualization as being the “cure” to disaster recovery, many for the past several years. Disaster recovery can be pretty reasonably viewed as being high-availability over distance, so it makes some sense to see how DR, HA and virtualization fit together. What’s hype here, and what’s real? Let’s look and see what we find out.
What is virtualization?
Wikipedia defines virtualization like this:
In computing, virtualization is a broad term that refers to the abstraction of computer resources. One useful definition is “a technique for hiding the physical characteristics of computing resources from the way in which other systems, applications or end users interact with those resources”.
At the moment, this term is most commonly used to refer to machine or OS-level virtualization, storage virtualization and something I’ll call container virtualization. For now, let’s ignore storage virtualization. Machine-level virtualization means basically making it difficult to tell exactly which physical machine an OS is running on at any given point in time. There are many other kinds of virtualization as well – for example service virtualization. Service virtualization doesn’t hide or abstract physical machines, but instead virtualizes or hides services. That is, there is no fixed binding between services and physical machines. This is, in fact, exactly what classic HA software does – software like Linux-HA http://linux-ha.org/. What an HA system does is use service virtualization to recover from server failures, and monitors services so that it can restart them – either locally or on another server.
To learn more please read the entire article at its source: Managing Computers with Automation: Virtualization as High Availability (Disaster Recovery) or High-Availability as Virtualization?