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while AMD called their extension AMD-V. Although the two are implemented differently, the idea is the same: certain
expensive operations which have previously been executed in software should be hardware assisted.
Benefits of virtualization
The major vendors for virtualization products are keen to point out the advantages of platform virtualization.
There are for example:
•
Reducing cost (there it is again!) by better utilizing servers and all in all reduce the footprint in
the data center
•
Increase manageability
•
Better ability to address a change in demand for resources
•
Easier planning for disaster recovery
•
Enhanced security
The cost aspect does not require a lot of explanation. It should immediately become apparent that by reducing
the number of servers drawing power, there is less of a requirement for cooling, energy, and rack space. By better
utilizing the existing servers less capacity is wasted idly.
Manageability is increased, and common “reference” templates make it very easy to get started with a new
technology. “Standard” operating system images can be used as templates from which new virtual machines are
rolled out very quickly. Oracle provides a wealth of pre-created templates for Oracle VM—the company's premier
enterprise virtualization product for the x86-architecture. Oracle's competitors in the market, such as VMWare, use
the same concept. In their language the getting-you-started-quickly Virtual Machines are called virtual appliances.
Most commercial virtualization solutions feature a management interface for the administrator allowing him to see
the state of his virtualized server farm. The better these management interfaces, the more likely the adoption of the
product in the enterprise.
Another key element in virtualization is the potential to react to changed user demand. Many virtualization
products allow the dynamic addition and removal of operating system resources at the virtual machine's runtime.
Imagine that the virtual machine requires more virtual CPU power for an important batch run. The administrator can
grant a few more cores to the VM at runtime or otherwise increase computer resources. Live migration of a virtual
machine has its main use in maintenance operations, but the flexibility to shuffle virtual machines around in the farm
is very useful.
Finally, executing a workload on a virtualized platform offers more mobility in planned and unplanned
downtime scenarios. For example, if the underlying physical hardware does not provide enough computing power
then a live migration to another host can keep the users connected while the guest is moved to another server in the
same farm. Similarly, disaster recovery solutions can be developed so that the impact on the service is minimized.
If a virtualization vendor does not provide a product for the Disaster Recovery (DR) case, then it is usually possible
to create one's own.
More virtualization options
Apart from platform virtualization, there are other forms of virtualization to explore. From an Oracle DBA's point
of view the most important virtualization strategy is the use of operating system virtualization. The term is again
somewhat loosely defined, but consensus seems to exist around the fact that an operating system can execute
multiple isolated instances of itself. Good examples for operating system virtualization are Solaris Containers, and to a
degree IBM Logical Partitions (LPARs).
Take a Solaris zone for example. Unlike hardware virtualization, a Solaris container cannot execute another
operating system. This slight disadvantage is more than made up by the fact that the overhead with this virtualization
method is very low. Solaris containers or zones are a very popular way to make better use of existing hardware,
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