Running multiple operating systems on one computer couples the
strengths and capabilities of those OS’s while
requiring that you only buy one computer. Who
hasn’t been running one OS and wished that they could run a program that only runs under another? Who hasn’t experienced an OS problem and
could boot into another system to resolve it?
computer refurbishing, running multiple OS’s allows you to
combine the strengths of an existing Windows install with those of open
source. Case in point: Windows XP is aging but still has
tons of how-to websites, great ease-of-use, thousands of applications,
and drivers for every device. Keeping it retains the original
software license, the installed applications, and the existing drivers.
(Past articles have described how to secure and
performance tune mature Windows systems.)
Add a Linux distribution and you gain all the
benefits of open source software — a free and currently supported operating
a state-of-the-art OS that runs on older hardware
than Windows 7 or Vista, security without anti-malware overhead, and
tons of free applications. A well-chosen distro greatly
expands the capabilities of an aging Windows computer.
Here are the ways to run multiple operating systems on a single system …
Live CDs and Live DVDs
Live CDs and Live DVDs allow you to easily boot and run alternate
operating systems. Just download a bootable OS image, burn it to disk,
set your computer to boot from the optical disc drive, and you’re
One big benefit to Live CDs is that you’re guaranteed a
malware-free OS. Some experts
against doing your banking and finances online, or they say you should
not use Windows if you do. Live CDs offer higher security for online
banking. Every time you boot from the Live CD you initialize a
fresh uncontaminated system, because the read-only disc can not be
altered by malware. (Of course the original Live CD has to be virus-free but I have yet to hear of such contamination.)
You don’t have to alter anything on your existing hard disks to run a
CD. No fiddling with partitions. You don’t even have to mount your internal disk.
Live CDs are a risk-free way to try out and play with as
many different OS’s as you’re willing to burn CDs for.
Whether you’ll be happy with the performance of running an OS from CD
or DVD depends on the speed of your optical drive and the OS you run.
Most people are satisfied using current optical drives, even for
full-sized Linux distributions that continually access the disc while
running. If you’re refurbishing an old computer
and frequently run live CDs, check the speed of your
optical drive and get a newer one if you need to. Drive speed has
dramatically increased over the past
Another trick is to use a distro that runs entirely from memory and
never accesses the CD/DVD or hard disk after booting. Puppy Linux, for
example, runs entirely in memory
on systems having just 256 M or more. It performs well even on
older computers. After booting you can use the CD drive for purposes
other than running the OS. The only small drawback is the startup time it
takes for the CD or DVD to initially load the OS into memory.
Live USBs are a
variant on the Live CD/DVD concept. In this case you use a USB memory
stick, flash drive, or USB external disk drive to boot and run the
Like live CD and DVDs, live USBs are portable. You can boot an
OS once this way to try it out, or you can work this way
regularly. USBs offer writeable, persistent storage. Memory sticks have
no moving parts so
they have better access times than optical discs.
downside to USBs is that many older systems won’t boot from
them. This is a BIOS
limitation. Circumvent it by using a boot
manager that boots the computer from a device your BIOS supports, then
control to the USB device. PLoP is one free boot manager. Another potential downside to USB booting is shortened lifespans
for USB memory, due to its constant use as the OS resident media.
has matured in the past five years. Hardware
technologies like Intel’s VT-x
and AMD’s AMD-V
underlie and improve it. These were introduced in 2005 and 2006, respectively.
This chart lists
and compares platform virtualization software. Oracle VM VirtualBox
is probably the most popular free offering for personal use. Once owned
Microsystems, the product was taken over by Oracle with their
acquisition of Sun in January 2010.
VirtualBox installs under an
existing host operating system,
then creates one or more virtual
machines in which various guest
run. The possible host includes most popular operating systems, such as
7, Vista, Windows XP, Linux, Mac OS X, Solaris, and some BSD versions.
the host systems plus even some lesser known contenders, like Haiku,
OS/2 Warp, Syllable, SkyOS, ReactOS, and the rest of the Windows and
VirtualBox offers all the advantages of platform
virtualization. These include
the abilities to:
- Securely run more than one OS at a time
- Flip between the systems as you like
- Start, stop, and pause the systems independently
- Communicate between systems through several mechanisms
- Dynamically allocate and switch processor and memory resources
among the systems
- Make an image of a current system state for backup/restore by taking a snapshot
VirtualBox does not require CPU-based virtualization support (VT-x
or AMD-V). But it does require the cumulative resources to run all the
OS’s you want to at one time. Thus it may not be an option for
some refurbished computers. If your computer supports it,
virtualization is a great way to go. Get
started with VirtualBox with tutorials from here
Co-Installing to Disk
If virtualization and Live CDs don’t appeal, you can
always go the traditional route and install more than one operating
system to disk.
Assuming the computer already runs Windows and you want
to co-install a Linux distro, the typical procedure is:
- Boot the Live Linux CD for the product you want to install
- Shrink the Windows partition to create sufficient space for the
- Create a new Linux partition in the newly-released space
- Optionally create a swap partition for Linux virtual memory
- Install Linux into the new Linux partition
- Install a tool like GRUB or LILO to display an OS selection menu
upon system start-up
- Reboot and verify the OS selection menu and the new Linux install
Let’s walk through the steps.
First you boot a Live CD or DVD for the Linux you want to
install. This allows you to test and ensure the distro drives all your
computer’s devices and works the way you want — before you install anything. It also creates a
working environment from which you can perform
the subsequent steps. Most distros provide the partition
management and boot control tools you’ll need. Ubuntu and Puppy
example, both offer Live CDs that bundle the GParted partition
manager and the GRUB boot-selection
Assuming the computer came with a single disk with Windows installed,
you’ll probably need to shrink the Windows partition to make room for
Linux. How much space Linux requires depends on the distribution. A
small Linux like Puppy installs easily in a gigabyte or even
500 megabytes, while a full-sized Linux like Ubuntu typically requires
anywhere from three to eight gigabytes.
Beyond the operating system partition, you may also want to create a swap partition.
Linux uses this disk space for extra memory (or virtual memory)
if real memory runs out. Do you need a swap partition? Think of it this
way. What is the maximum size of memory you’ll require for the Linux
operating system plus the maximum number of applications you’ll have
open at one time? If this amount is greater than the size of real
memory, you need a swap partition to make up the difference.
Since users run different distros and use their computers in
different ways, it’s not possible to devise an all purpose
rule-of-thumb for sizing swap space. Running typical home and office applications, for
example, I never use the swap if the computer has at least 1 gigabyte
of RAM. Specialized applications change this recommendation. For
example, when I do database testing and research, even computers with
several gigabytes need swap space.
next step to installing Linux on a Windows computer is to ensure you
have some free disk space on which to install Linux. You may have to
reduce the size of the Windows partition on a single-disk Windows
system because, by default, many
vendors still pre-install Windows
to consume the entire disk.
It’s wise to run a Windows Disk Check prior to shrinking the Windows
partition to ensure file system integrity. Then use the GParted Linux tool to shrink the Windows partition.
You do not need to run the
Windows defragmentation utility prior to this operation — contrary to
what you might read elsewhere on the web. GParted successfully shrinks NTFS partitions regardless of whether they have been defragmented.
At this point you have a target partition ready into which to
install Linux, and optionally, a swap partition. Now you can install
Live Linuxes have an “install icon” on their desktop that you click to
process. Although I’ve discussed getting the partitions ready prior to
running this install tool, many Linuxes (such as Ubuntu),
partition management tool as a step within their standard install
In other words, you can either manually do the partition management in
advance, or do it while you run the Linux distro installer.
Here’s an example of GParted in action. This screenshot shows what you
can do with multiple operating systems even on an old refurbished test machine with two tiny 40G disks. This
system has four operating systems
installed on its primary drive. This includes a 13.67 gigabyte NTFS
partition with the original
Windows XP SP3 install. Then there are Linux partitions for Ubuntu,
Puppy, and Vector Linux. The
single Swap partition of about 510 M
whichever Linux runs. A second 40G disk drive (not shown), contains
three more Linux distros, three backup partitions, and a BSD variant. Quite a lot of action for an old computer!
An Example GParted Screen
The first line in the above display is a FAT32 partition on which all
data resides. Storing user data apart from any of the
operating system partitions is wise because it segregates data from the
operating systems. This makes it easy to identify and back up user
data. Moreover, the user data remains
unaffected regardless of what changes you make to any of the
operating systems or their partitions. Should an “OS disaster” occur
it’s unlikely that data on its own partition will be affected.
is unfortunate that many
consumer computers by default still store user data on a single
Windows partition that consumes the entire disk. This practice is a
hold-over from the days when
disks were smaller and it doesn’t leverage the advantages of
larger disks. With big SATA drives it makes
much more sense to segregate data and OS partitions. I know some people
who even separate out certain kinds of data files into their own
partitions. For example, you might have a “multimedia partition” for
photographs, music, or videos. This makes it easy to separately manage
files. Or segregate your work from your play by creating an “office
partition” for office suite documents. Easy partitioning makes it
possible to organize your system in the way that works best for you.
When adding Linux to a Windows computer, you’ll install a boot manager,
In Ubuntu and Puppy,
this is an option in the last step in the install process. GRUB takes
over the master
boot record or
MBR on the computer’s disk and inserts code that displays a menu
to select any of
the resident operating systems when you start the computer.
about your existing Windows being bootable. GRUB is very good at automatically
detecting any operating systems already on your hard disk. It generates
the necessary code to make them boot-time selections. So GRUB will find
Windows and automatically place it in your new boot-time OS selection
When the install is complete, reboot your computer and you’ll see GRUB’s menu with options to enter either
Windows or Linux. Try both out to ensure everything works
ok, and you’re done. Voila! Multiple OS’s on your computer.
Once you’ve gotten everything working, you might want to make
the boot-time OS selection menu more readable. If you used GRUB,
just edit the
file menu.lst in the /boot/grub folder. (Save the original menu.lst
file first as a backup!) If your Linux distro uses the newer GRUB 2,
well, there are many advantages to this new boot loader, but easy
changes to the boot menu is not among them. See this excellent tutorial
for help. It’s too bad that GRUB 2 is a step backwards for ease of use,
especially since it would have been easy for the product to use a menu.lst file if present and convert it to the required internal code.