33
risks. By consolidating provided by mission-critical “live-tests,” for example,
multiple servers that perform applications. This must switchovers during planned
TECHNOL
a variety of business critical happen in all situations, from maintenance are often
functions onto a single host component failure through implemented in order to gain
system, availability of that user error to natural disaster. experience on the virtual
system becomes a significant The critical component in all machine, before switching
OGY
risk point. VMware has taken of the above is the back seamlessly to the
some huge steps to mitigate application itself, and it is not physical server and analysing
these risks with high possible to deliver continuous the test results before a final
availability and business availability without switchover.
VIR
continuity products to protect understanding the
from the failure of the performance and availability VMware’s Virtual Infrastructure
TU
physical platforms on which of individual applications. contributes class-leading ALIZ
virtualized applications run. levels of high availability
In many cases, the first risk to focused on maintaining
A
TION
Organisations can take this a availability of mission-critical application availability. If a
step further with the applications is the physical- host system critically fails, all
implementation of to-virtual (P2V) migration virtual machines can be
application-centric solutions, process. The process itself restarted on alternate
focusing on individual will depend on the criticality hardware using VMware HA. If
elements, such as Microsoft of the application and hardware resource levels drop
Exchange and SQL Server. This whether downtime can be below acceptable thresholds,
granularity provides options considered acceptable. As it DRS can dynamically reassign
for high availability and involves cloning systems and the load to servers with free
disaster recovery that do not data, extensive testing is capacity automatically, before
rely on shared storage, thus required to ensure a the resource issue degrades
providing greater flexibility seamless, uninterrupted service. While this may
and lower cost options, switchover. A staged approach overcome the risk associated
particularly for remote allows time for evaluating the with the hardware and
disaster recovery within overall benefits and impact, operating system that
virtualised environments. This and of course, continuous supports a virtualized
combination offers customers availability of the virtualized application, it does not
complete protection to ensure environment must apply from account for the largest risk
the continuous delivery of day one. From the standpoint category with the highest
services for critical business of risk management, it would probability of failure –
applications. be ideal to adopt a migration problems that occur to the
strategy that also applications running within
The best way for IT to ensure accommodates an immediate the virtual environment.
consistent business and automatic failback of
performance is through the applications onto the original For example, if the Windows®
implementation of a physical platform should operating system running
continuous availability unexpected problems within a VM exhibits any form
solution that focuses on the manifest themselves within in of failure (such as a blue
business’ needs and end user the virtual environment. In screen); or if the virtualized
experience rather than fact many customers will carry network fails or is
storage-focused products out P2V migrations in stages. misconfigured; or if any of the
protecting data and hardware Firstly, they will clone the mission-critical applications
as isolated components. application to a virtual running within the VM itself
Continuous availability machine giving immediate exhibit problems, VMware will
demands there is no high availability options. They be unaware of the
interruption to services will then carry out a series of implications of the situation.
WWW.SNS-UK.CO.UK MAR/APR 09
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