Page 79 - How Cloud Computing Is Transforming Business and Why You Cant Afford to Be Left Behind

VIRTUALIZATION C HANGES EVERYTHING

It’s not a big mystery how this is possible. In effect, the hy-
pervisor figures out the part of an application that the virtual
machine is about to use and leaves that part running on the ex-
isting server, while moving all the other parts to a different phys-
ical server. The hypervisor moves the data that the application
doesn’t need at the moment to the same server, then, when all

is ready, it suspends the VM’s operation, moves the last 10 to
20 percent of the application code to the new location, and re-
sumes operation. It happens at the speed of light, in a few
thousandths, or at most hundredths, of a second. A perceptive
end user might notice a slight pause in operation, but most IT
managers say that the shift is imperceptible to most users.
Today, that migration can be performed by a cloud system

administrator or by automated software that’s been author-
ized to act under certain conditions. A service-level agreement
between the cloud supplier and the customer sets an allow-
able time for applications to respond to users. If that response
time is threatened, the automatic management system acti-
vates more resources one way or another so that the applica-
tion servers can quickly solve the problem.
In addition to the commercial systems that are capable of
doing this, some free open source code systems, such as

VMware’s Hyperic HQ management system, are giving cloud
customers the ability to peer into their cloud virtual machine’s
operation and deduce on their own what’s going on. This abil-
ity passes the ability to make management decisions by remote
control back to the end user, giving the end user even more
power.

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