Linux System Administration

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Chapter 9

CHAPTER 9

Virtualization in the

Modern Enterprise

In this chapter, we address an area experiencing explosive growth in demand for

Linux system administrators. Linux virtualization lies at the heart of today’s trends in

data center consolidation, high-performance computing, rapid provisioning, busi-

ness continuity, and workload management. Enterprises are seeing real cost savings

because of Linux virtualization, and analysts are noting that the technology is chang-

ing the business landscape.

Virtualization is a concept that has gained popularity thanks to the successful com-

pany VMware (http://www.vmware.com) and the open source project Xen (http://

www.cl.cam.ac.uk/research/srg/netos/xen). It refers to one piece of hardware running

multiple kernels (which are sometimes all the same and sometimes from completely

different operating systems) on top of a lower layer of software that manages their

access to the hardware. Each kernel, called a guest, acts as if it has the whole proces-

sor to itself.

The different guests are isolated from each other much more than processes are iso-

lated within a single operating system. This isolation provides security and robust-

ness, because a failure or compromise in one guest doesn’t affect the others. The

virtualization layer performs many functions of an operating system, managing

access to processor time, devices, and memory for each guest.

At ...