Information Technology Reference
In-Depth Information
Changes to asset tracking and run books (e.g., rebooting a physical computer
requires rebooting all of its VEs)
More care needed when assigning workloads to computers: The computer
and the virtualization technology represent a single point of failure for al-
most all technologies.
Potential for increased or new costs:
A computer using virtualization may be larger than a single-workload sys-
tem and, therefore, more expensive.
The level of support needed for a computer using virtualization will often
cost more than the level of support for the least important of the workloads
being consolidated; if most of the workloads were running on unsupported
systems, support costs might actually increase.
Data center architects and system administrators will need training on
the virtualization technologies to be used.
1.1.4 Other Reasons for Virtualization
After years of virtualizing solely to isolate consolidated workloads, people realized
that some of the benefits of virtualization can be useful and are worth the effort,
even if only one workload is present on a system.
One benefit is the business agility gained from simple VE mobility. The ability
to move a workload (called migration ) enables businesses to respond more quickly
to changing business needs. For example, you can move a VE to a larger system
during a day, instead of planning the acquisition of a new, larger system and the
reimplementation of the workload on that system. The VE provides a convenient
“basket” of jobs that can be moved from one system to another. Virtual machines
are particularly effective at providing this benefit.
Some tools even enable regular migrations to respond to periodic fluctuations
in demand. For example, a batch processing workload might have minimal pro-
cessing needs during the day but perform significant work at night. It could be mi-
grated to a small system with other light loads in the early morning and migrated
to a large system in the early evening.
Because VEs are convenient, manageable objects, other business needs can also
be addressed with virtualization. A snapshot (a complete copy of a VE) can be made
before the VE boots, or after its workload is quiesced. If the VE becomes damaged
while it runs, whether accidentally or maliciously, the workload can be quickly
restored. The data in the damaged copy can then be methodically inspected, both
for valid transactions that should be rerun against the workload and as part of
a thorough security analysis. Many file systems and storage systems include the
 
 
Search WWH ::




Custom Search