Server Virtualization - What It's All About
What is this "virtualization" thing all about? Are you tired of hearing about it in discussions
at your corporate meetings, reading about it in tech magazines, and feeling like you are being
left in the dark?
The term "virtualization" is referring to an operating system (such as Windows XP) running
without any dedicated hardware as a "Virtual Machine" (VM) running on a host computer. A basic
example of this is using a program like Virtual Box to allow the user to install and boot up
using Windows XP on a host PC with Windows 7.
As a real world example, let's say that in your office there are three old servers. One
is an old server that runs the company email and it has been running for over 8 years. Since
installing the server, your company has grown significantly adding 150 employees, and now your
email server is old and tired, the hardware is outdated and there are complaints in the office
about email slowness and downtime.
Your second server runs your active directory, DNS, and file shares. This server is also
starting to run slowly due to the age of the hardware and the addition of the new employees,
and the constant growth of the databases (inventory, customers, order history, etc.). You
are experiencing disk space issues.
The third server, let's say, is an old Red Hat Linux server that hosts an accounting program
that is proprietary to your company. This software interfaces with the second server and pulls
information from a database located in one of the shares and generates reports, etc. This server
also hosts a website that links into your inventory database for online customers to order from.
In connection is a portal for your sales team to check prices, shipping times, and order statuses.
As time goes on, parts for these older servers are becoming harder to find, drives are
starting to fail, and down-time is more and more common in the work place. One option is to
replace each of the existing servers, but this includes purchasing three new servers and replacement
licenses, installation and programming costs, and will result in weeks of downtime, which will
be extremely costly and interruptive to your business.
Virtualization is a much more cost-effective option which will result in only minimal downtime.
For this project, virtualization will likely require the purchase of one new server with multi-processors
or a multi-core CPU loaded with memory and a weekend of downtime at most.
Your manager or IT administrator can monitor all three virtual servers and the physical
server by installing a simple "management console" on his or her PC which can be used to view
the desktop, reboot the individual server, add resources such as printers and USB drives, and
nearly any other task.
XenServer is virtualization software designed for management of Windows and Linux virtual
servers and is developed by Citrix Systems, Inc.
Citrix XenServer also has many features, such as "automatic failover." Let's say that
you completed your new server implementation and everything is running perfectly. Now your
worry becomes that if something happens to your new server, your company could be at risk for
considerable downtime if you have to restore from a backup (assuming you have a reliable backup
system in place at all!) or become subject to downtime for maintenance, upgrades, etc.
You can introduce a second server and a shared storage solution such as a DataCore or Dell
EqualLogic SAN that both servers can access. When your second server is setup as a failover
server, if your main server shuts down or for any reason or if you need to shut it down for upgrades,
etc., the second server will automatically pick up where the first one left off so the user sees
little to no downtime or interruption. In fact, users are unlikely to even realize that they are now
accessing one server versus another!