SigLinux Friends,
this article [from TechSoup.org - a resource for nonprofit
organizations] on virtualization software available in open source
caught my eye. Allow me merely to share this article. Perhaps one of you
can use it as you orient persons wanting to operate linux and microsoft
on the same computer without the need to use/understand partitions and
all the junkie cross over procedures I have seen so many of us suffer
with back down the line. Besides the date of this computer mentor's
article is 8-19-05. Enjoy! Kenneth
Virtualization Software: A Computer Inside Your Computer
Run multiple operating systems on one PC
*By: *Joseph D. Foran
*Source: *TechSoup.org <http://www.techsoup.org>
Virtualization software (VS) is a way of running multiple operating
systems on the same computer, all at the same time. It's like having
many computers inside your computer.
Traditional methods of running multiple operating systems (by
partitioning your hard drive and creating a dual-boot) have two main
limitations: only one OS can run at a time, and the physical hardware on
the computer limits your choices. (For instance, you can't run Mac OS on
a PC in most cases.)
Virtualization changes this because the software runs as an application
on your computer and emulates hardware, so hardware compatibility isn't
an issue. Simply start the virtualization program, and it pretends to be
a computer. Each operating system you install on your PC will act as a
new computer. For instance, I have a computer with VS installed that
runs as a Linux server, two Windows servers, and three other Linux
servers -- for a total of six servers that I can access at the same time
(five guests and one host) through one PC. On the network, each server
appears as a unique system. I can run programs, share files, and do
anything in these guest systems that I could do with a real computer.
Under the hood, VS is a software application, much like Word, Excel, or
Firefox. To get started, power up your computer, insert an operating
system's install disk into your DVD or CD drive, and install the guest
operating system(s). (When you install operating systems in an emulated
hardware environment, they're called "guest" operating systems or
Virtual Machines, or VMs, while the main operating system is called the
host.) Once you've installed the guest operating systems, install and
configure your VS.
Using VS greatly cuts the costs of setup and breakdown time for testing
any kind of software development -- it's like having a lab of ten
systems, all on one box. For example, some IT departments will install a
standardized version of Windows that can also set up all of a user's
programs automatically. So basically, an organization would buy a
computer, somebody in IT would stick in a CD or boot from the network,
and come back in two hours to a ready-to-go system.
Naturally, when necessary changes or upgrades will alter the systems,
testing is required. To do this without VS, a lab would need to set up
with computers, network gear, and other expensive hardware. With VS, the
new build process can be tested quickly, reliably, and with consistency.
And the savings in hardware result in a significantly reduced cost.
Most commercial VS packages are easy to set up, but take some tweaking
to perform at top speed. Most Open Source packages, however, still
require heavy tweaking. Xen, in particular, (more on this in the next
section) requires a whole different setup to be completed before
installing Mac OS.
The Many Sizes and Flavors of VS
There are several vendors offering varying types of VS software, some
packages cost thousands of dollars while others are Open Source programs
that cost nothing. The application that fits your needs depends on how
many computers you have, what sort of work you're doing, your level of
technical expertise, and what kind of tech support you'll need.
Both Microsoft Virtual Server 2005
<http://www.microsoft.com/windowsserversystem/virtualserver/default.mspx>
and VMWare <http://www.vmware.com/> sell software packages, while, Bochs
<http://bochs.sourceforge.net/>, and PearPC
<http://pearpc.sourceforge.net/> provide Open Source virtualization apps
that won't cost you a dime.
Virtualization comes in three sizes: small, medium, and large. VMWare
Workstation 5 <http://www.vmware.com/products/desktop/ws_features.html>
and Microsoft Virtual PC 2004
<http://www.microsoft.com/windows/virtualpc/default.mspx> are examples
of the smaller types of VS and are geared toward running on
workstations. They're best for testing new software or piloting IT
infrastructure changes.
In the middle category are Xen, Bochs, and PearPC. Xen and Bochs are
virtualization software for Open Source operating systems like Linux and
BSD. Since these operating systems are suitable for use as either
workstations or servers, Xen and Bochs fit well into both categories.
Likewise, PearPC can run workstation or servers as virtual machines, and
can run on workstation or server computers. The main difference is that
PearPC is designed to emulate PowerPC architectures, namely the G4
processor. Hence, its main use is for emulating Apple hardware on
non-Apple machines. I use PearPC to run OS X Jaguar on an HP Laptop
running Windows XP, for instance.
The higher-end products like VMware ESX
<http://www.vmware.com/products/server/esx_features.html> and Microsoft
Virtual Server 2005
<http://www.microsoft.com/windowsserversystem/virtualserver/default.mspx>
are designed for "server consolidation," the art of using fewer servers
to do the same amount of work. Most servers do their jobs while using 20
percent or less of their resources utilized (RAM, processor, disk
space), so using the same hardware to support multiple servers makes
sense, pushing utilization closer to 100 percent. This means that the
expensive hardware is being used to its fullest, and money is saved on
not having to buy server hardware that will just loaf around at under 20
percent utilization. These VS products are meant for data centers, or at
the very least, organizations that need five or more servers.
Cost and Support Considerations
There's a cutoff point for any product, when it makes sense to use it
and when it's not cost-effective. VS is no different. If you're a small
organization with only a few servers, moving to virtual servers isn't
for you. If you need to deploy more than five servers in the immediate
future, VS will save you lots of money on hardware. The best advice here
is to do lots of research and determine your needs versus
virtualization's cost.
Bochs, PearPC, and Xen don't cost anything and they're Open Source, too.
That's the good news. The kicker is that none of them is easily
installed or configured. If that hasn't scared you off, the best route
is to make a time and training investment to bring staff up to speed on
how to use the products. (As of this article, PearPC was still in a
beta, meaning that the current version is still being tested and isn't
considered stable enough for use in production systems.)
With these programs, support is an area of contention -- Bochs and
PearPC lack formalized support on their own, instead relying on
community-based support forums and mailing lists. Novell provides
commercial support for Xen for those who buy the commercial version of
SuSe Linux, and a new company called Xensource
<http://www.xensource.com/> has been formed as a Xen vendor and service
provider.
Of the commercial vendors, Microsoft's software costs the least, but it
comes with a caveat: You can only run Microsoft guest operating systems
and you have to run the Virtual Server or Virtual PC on a Windows host.
If you need to run Linux as a host operating system, then Microsoft's
Virtual Server (or Virtual PC) isn't a viable option. But if you're
planning to run an all-Microsoft shop, Microsoft's Virtual Server is an
excellent choice, as it is far less expensive than VMWare and you can
run as many guests as your hardware can support. Versions for the Mac
are also available and let you emulate PC hardware on Apple hardware.
Though expensive, VMWare runs on Linux or Windows hosts, and includes
some of the best support available. It supports a wide variety of guest
operating systems, including Linux, Windows, and BSD on emulated Intel
hardware (which means it can't run Mac OS X). There are also
VMWare-specific programs out there to assist with migrating physical
servers over to virtual machines, and there are even multiple levels of
VMWare for different businesses.
The Bottom Line
As always, you'll need to license your software per server, whether
they're virtual servers or physical servers. Suffice it to say, you'll
never save money on software licenses with VS technology. Your savings
occurs in hardware. That is, if you plan to buy servers where the total
hardware cost would be more than twice that of virtualization software,
go the VS route. Non-profits can often get licenses for software at a
discount, so take this into account as you're making your decision.
Additional Resources and Installation Help:
DevX.com: Add Virtualization to Your Development Toolbox
<http://www.devx.com/enterprise/Article/27918/0/page/2>
WindowsSecurity.com: Using Microsoft Virtual PC to test software
<http://www.windowsecurity.com/articles/Microsoft-Virtual-PC.html>
Linux Journal: Bochs: A Portable PC Emulator For Unix/X
<http://www.linuxjournal.com/article/1310> , including information
on installation under Linux
Microsoft Virtual PC 2004 Evaluation Guide
<http://www.microsoft.com/windows/virtualpc/evaluation/evalguide.mspx>
Xen documentation, FAQs, and downloads
<http://www.cl.cam.ac.uk/Research/SRG/netos/xen/>
How to install VMWare
<http://www.vmware.com/support/ws4/doc/new_guest_tools_ws.html>
TechSoup thread about differences between VMWare packages
<http://www.techsoup.org/fb/index.cfm?fuseaction=forums.showSingleTopic&forum=2009&id=58530&cid=117&cg=searchterms&sg=vmware>
Article date: August 19, 2005
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