
198
|
Chapter 9: Virtualization in the Modern Enterprise
Each VM lives in a directory. For example, our main directory, /var/
lib/vmware/Virtual Machines, contains several subdirectories such as
debian-31r0a-i386-netinst-kernel2.6. We simply compressed that sub-
directory and used it for deployment to other subdirectories with
slightly different names.
We also set up Xen virtual machines using Fedora minimal installations. We then
added the components we needed for each service we wanted to provide. For exam-
ple, our primary DNS server runs in a Xen virtual machine, while our web and mail
servers run in separate instances of VMware.
After we got a server (say, email) running, we made a compressed copy of it and
burned it to a CD-R. We regularly and systematically back up each virtual server
onto visual media such as CDs and DVDs. We also tried moving the images to differ-
ent distributions of Linux, and they ran just as they had previously.
How Virtualization Helps
What did we accomplish with virtualization? First, we eliminated several physical
servers. We deployed our preferred operating system as an image, so we needed to
go through the installation process only once. We then created virtual machines on
spare hardware and systematically copied our virtual images to allow for instant
recovery in case of a system failure.
Virtualization works well for small companies, allowing them to build an