cee oh em gee tee - "commgitt"


We have more than a decade of experiences in desktop virtualization.
Contact us for assistance with setting up your own virtual environments.

Virtualization - example of real use
   Introduction to Desktop
   BackTrack in 30 Minutes
PDF, quick guide to get started
Presentation March 2010
Presentation from March 2010
(19 slides)
  Introduction to Desktop Virtualization
2012-10-20 For review

(19 pages)
  BackTrack in 30 Minutesd
(BT 4 but in principle valid for any BT,
(all documents opens in a new tab/window)

Separate sections:



General Information top

Learning center



Planning top

Some topics to consider:



The Perfect Host top

(Updated Sep 2011)

This is of course very much an opinion and your personal requirements and needs will ultimately determine what is your perfect host.

  Mac-based (Mid 2011) Windows-based Notes
System iMac 27" Higher-end Dell, HP, ...  
CPU Intel Core i7, 3.4 GHz <-- (aim for) Multiple cores, big cache, fast
RAM 16 GB (max) -"- Essentially as much as you can afford
Disks 1) 250 GB SSD
2) 2 TB traditional HD
-"- Fast SSD for booting OSs, start apps, ...;
Traditional HD for data. More below under SSD and Traditional Hard Drives.
Monitor(s) 1) 27" 2560x1440
2) 24" 1920x1200*
-"- Multiple monitors are always recommended (not only for VMs)
*And 1200x1920 - rotate for viewing long documents
I/O Gigabit Ethernet
802.11n Wi-Fi
Host OS Mac OS X 10.6 Snow Leopard
or Mac OS X 10.7 Lion
Windows XP 64-bit (below) (Mac OS X is 64-bit since 10.6, no 32-bit variant exist)
  included BSD-kernel,
*NIX env.
(no) Mac OS X is Mach/BSD-kernel - based and offer easy use of *NIX commands and even X-Windows GUI applications. It's also easy to compile and run many open-source applications straight out of the box. (Need to install the included free Xcode development environment and BSD subsystem. Everything is on DVD included with the computer.)
Guest OSs Essentially any OSs*
including Mac OS X Server
Essentially any OSs*
excluding Mac OS X Server
*Any *NIX, Windows, ... depending on EULA (End User License Agreement)
(Mac OS X Desktop is not permitted for VM use.)
Access to:      
Mac OS X DT ckh (std) - Mac: Obviously - Mac OS X Desktop is the host OS and thus available
Mac OS X Srv ckh (add) - Mac: Can run Mac OS X Server OS in virtual environment
Mac OS 7-9 ckh (add) - Mac: see (e.g.) for running older Mac OSs.
BSD-env. ckh (std) - Mac: underlying technology (kernel and terminal, command line interface (CLI), commands) is BSD-based. Add BSD-subsystem (on system disk that comes along the computer) for also development, building sources, etc.
MS Windows ckh (add) ckh (std) Mac: Boot into (Boot Camp) or in VM. Win: Host OS and thus standard
Linux distros ckh (add) ckh (add)  
Chrome OS ckh (add) ckh (add)  
Solaris ckh (add) ckh (add)  
Many more ckh (add) ckh (add) See (e.g.)




SSD and Traditional Hard Drives top



Windows Host OS top

(Added September 2011)

We actually strongly recommend staying with Windows XP as host OS for Windows-based host machines - and stay away from Windows 7. I.e. - at least if going for 64-bit variants, which you most like would. You want as much memory you can afford.

Instead go with Windows XP 64-bit:

If you really want Windows 7, run the 32-bit (or 64-bit) in a virtual machine.

A brief comparison table with requirements for a few operating systems:

Vendor Operating System Min HD Min RAM Comments
Microsoft Windows XP 32-bit 1.5 GB 64 MB  
Windows XP 64-bit 1.5 GB 256 MB  
Windows 7 32-bit 16 GB 1 GB  
Windows 7 64-bit 20 GB 2 GB Compare w/ XP 64-bit... As host OS, XP is leaner and significantly less
demanding on available resources.
Apple Mac OS X 10.5 Leopard 9 GB 512 MB  
Mac OS X 10.6 Snow Leopard 5 GB 1 GB One main goal w/ 10.6 was optimizing size and speed.
Mac OS X 10.7 Lion 7 GB 2 GB New features in Lion like Auto Save and Versions
compensate for higher requirements.




Comparison Selected Mac Systems top

A few systems we have been / are using. (Tried using a Windows 7 64-bit host system for a few months but had continous problems with performance, drivers and even crashes of hypervisors - VirtualBox (freee), VMware Player (free), and Workstation ($$$).)s

  MacBook Pro
(Mid 2009)
iMac 27"
(Mid 2010)
iMac 27"
(Mid 2011)
Speedmarka (15", 2.8 GHz, 4 GB) (27", 2.93 GHz i7 BTO) (27", 3.4 GHz i7 BTO)  
  v6.5 (127*) 225 (org test) 298 (org test) *used v6.5 / 1.1 (110/100)a
  v6 140 (recalc?) (247*) (328*) *used v6.5 x 1.1 (110/100)a
  v5 260 (org) (n/a) (n/a)  
CPU 3.06 GHz Intel Core 2 Duo b 2.93 GHz Intel Core i7 b 3.4 GHz Intel Core i7 b  
  #CPUs 1  
  #Cores 2 4  
 L2 Cache 6 MB shared 256 KB per core  
 L3 Cache na? 8 MB 6 MB  
Bus speed 1066 MHz 1333 MHz  
RAM 8 GB b (DDR3) 16 GB b (DDR3)  
Disk(s) 500 GB SATA 7200 rpm c 250GB SSD + 2TB 7200c  
Optical SuperDrive 8X DL  
Graphics 1) NVIDIA GeForce 9600M GT
2) NVIDIA GeForce 9400M
ATI Radeon HD 5750 AMD Radeon HD 6970M  
  Memory 512 MB GDDR3 1GB of GDDR5 2GB GDDR5 b  
Monitor(s) 15.4" 1440x900 27" 2560x1440  
- Ethernet 1 (Gigabit)
- Thunderbolt - 2 (up to 10 Gbps)
- FireWire 800 1 (up to 800 Mbps)
- USB 2.0 2 4 (up to 480 Mbps)
- monitor 1 Mini DisplayPort  
- SD 1 SD card slot 1 SD card slot (SDXC) 1 SD card slot (SDXC)  
- WiFi 802.11a/b/g/n draft 802.11a/b/g/n 802.11a/b/g/n  
- Bluetooth 2.1+ EDR  
- Audio In Combined opto dig and ana  
- Audio Out Combined opto dig and ana  
- Video In iSight camera;
input via DisplayPort
and sep. adapters
iSight camera;
input via DisplayPort
and sep. adapters
FaceTime HD camera;
input via DisplayPort
and sep. adapters
- IR receiver Yes Yes Yes  
More kb/SP544 kb/SP588 kb/SP623  
a From ('Roughly: A Speedmark 6.5 score of 100 = S6 of 110 = S5 of 220 = S4.5 of 400')
b Upgrade - BTO: Fastest available option (CPU), max memory that can be installed (max supported by HW, SW), ...
c Largest and fasted mechanical hard drive option






Products - Hypervisors top

Overview of some products:

  Host Operating System  
Origin Mac OS X MS Windows *NIX Notes
Major Players, Hypervisors
Parallels Desktop
for Mac
for Windows
& Linux
for Windows
& Linux
VMware Fusion ($$) Player (free),
Workstation ($$$)
More in our
VMware section
? Not researched if have *NIX solution
VirtualBox for OS X
for Windows
for Linux &
Open source project
Emulation / not complete virtual machine monitor (VMM) solutions
n/a CrossOver
Cygwin (No need*) Yes n/a Linux environment for Windows.
*Mac OS X being BSD-based has out-of-the-box
same capabilties as cygwin - libraries, tools,
means to recompile open sources, ...
Wine ? n/a for many
*NIX flavors
Open source project (GNU LGPL)
(Virtual PC no longer Windows 7 no longer see below)
Tools Useful in Cross-Development (Not Directly Related to Virtual Machines but can come handy...)
Minimalist GNU for Windows
n/a Yes n/a Building native Windows apps




New Versions Sep 2011 top

Both Parallels and VMware came out with new versions in September 2011:

  Parallels Desktop 7 VMware Fusion 4
  PC Mag Sep 29, 2011 PC Mag Sep 29, 2011
Editor's Rating 4 of 5 - 'Very Good'
4.5 of 5 - 'Very Good'
PC Editor's Choice
Pros "Runs Windows and other operating systems on the OS X desktop. Tight integration of Windows apps with OS X. Fast performance. Many options for importing an existing Windows system." "Runs Windows and other operating systems on the OS X desktop. Tight integration of Windows apps with OS X. Low-clutter, customizable integration between Windows and OS X. Works well with legacy applications under Windows XP. Simple setup."
Cons "Some excess desktop and file clutter; glitches with legacy apps running under Windows XP. Setting up Windows networking is more involved than with VMWare Fusion. Costs more than Fusion." "Very slightly slower than Parallels Desktop in some functions."
Bottom Line "One of two superb OS X apps (the other is VMware Fusion) that let you run Windows or Linux in tight integration with OS X itself." "One of two superb OS X apps (the other is Parallels Desktop) that let you run Windows or Linux in tight integration with OS X itself."


  Parallels 7 Fusion 4 VirtualBox 4
Version compared 7.0 ### 4.1.8
Downloaded 2012-02-08 2011-10-25 2012-03-11
Size 319 MB ### 91.6 MB




New Versions Sep 2012 top

Both main vendors of hypervisors continue to release new version at about the same time in the year.





Appliances top

Ready-to-use virtual machines (operating system, applications, ... on virtual disk for immediate use with hypervisor(s)). Simply download, unpack (these are most often big things and are distributed in some compressed format, like zip) and open with the hypervisor application.




Distros - Distributions top

(Content consolidated to our Linux library section.)




Files - Virtual Hard Disks, Configuration Files, ... top



Types of Files top

Configuration files, virtual hard disks, ...

    Support By  
File Description Parallels
Virtual Manager
Virtual Machine Configuration Files (open - double-click - to start a virtual machine)
.ovf Open Virtualization Format
no (v6)  
.pvm Parallels Virtual Machine      
.vmwarevm1 VMware, Mac     on Mac
.vmx VMware, Mac / Windows      
.vbox VirtualBox main file      
1 NOTE: This is one of these special 'files' on a Mac (like .app) - the GUI (Finder) treats it like a file but
it's actually a folder. Use Show Package Content to view contents.
Virtual Hard Disk Formats (specifically created for use with virtual machines)
HDD Hard Disk Drive
Native ?1 ?1  
    ?1 ?1  
VDI Virtual Disk Image
?1 ?1 Native  
VHD Virtual Hard Disk
- - Can mount on Mac.2
VMDK Virtual Machine Disk
?1 Native ?1  
1 To research / not tested yet
2 Also tried to directly use the format for creating machines in Parallels, VMware Fusion, and VirtualBox (all on Mac)
but none immediately accepted this format. Need to further research converting .VHD-files to other format(s).
Other (mentioning a few as so easy to use, on Mac OS X i.e.)
Apple Disk Format yes yes yes once mounted
.iso ISO image yes yes yes once mounted
(The above immediately mounts on a Mac OS X system without any additional software.
MS Windows systems typically need additional software for mounting onto file system.)



Where To Find Files (Mac) top

Good to know when looking for details:

Product Locations What
Parallels $HOME/Documents/Parallels/ .pvm config files
VirtualBox $HOME/Virtual Hard Disks/ disks; big things
$HOME/VirtualBox VMs/ configuration files
VMware Fusion $HOME/Library/Application Support/VMware Fusion/... .vmwarevm config files




ovftool, By VMware top

Open Virtualization Format (OVF) command line interface (CLI) tool by VMware, for for importing and exporting OVF packages.

The tool is free and avaialable for Mac, Windows, and Linux. Again, a CLI- and not GUI- tool.




Backups top

Virtual machines often involve really big files! And any minor change can result in lengthy backups. Contemplate the following figures:

And just opening the virtual machine changes files within and thus marks the virtual hard disk file and related files for a new backup.

So, what solutions are there?

  1. Exclude backups of (specific) virtual machines. If VMs are only for test and play and you don't care about loosing some work. (Host OS).
  2. Create separate backup schedules for virtual machines. (Host OS). Different time schedules and use of different backup storage areas.
  3. Set up backup handling from within the virtual machine itself (Guest Os). This can be quite a lot of additional work for the average user.
  4. Use specific software for backups of virtual machines - this is a relatively new area and products are still evolving. Many are only focusing on data centers (with corresponding costs involved) and we haven't seen any good and easy-to-use solutions for desktop users yet (Jan 2011).

For most desktop users, we recommend either option 1 or 2. You don't want to backup your VMs to your online storage, which for every minor change could take hours - if not days - to execute.





Finance top

(section started 2011-03-27)



Security top

(New section 2011-03-19)

US-CERT warns of guest-to-host VM escape vulnerability,, 2012-06-13

From Network World's Nproduct review (link below):

As enterprises move towards virtualizing more of their servers and data center infrastructure, the security technologies that are plentiful and commonplace in the physical world become few and far between.

While few direct attacks on virtual machines have been observed, it is still good security practice to protect VMs from potential vulnerabilities that exist only in the virtualized world.

For example, physical firewalls aren't designed to inspect and filter the vast amount of traffic originating from a hypervisor running 10 virtualized servers. And because VMs can start, stop, and move from hypervisor to hypervisor at the click of a button, protective features have to be able to handle these movements and activities with ease. Finally, few hypervisors have the access controls that even the most basic file server has: once someone can gain access to the hypervisor, they can control all of the VMs that are housed there.

In response to these concerns, a number of new vendors have created virtualization security tools. And the pace of mergers and acquisitions has picked up as the established vendors try to augment their offerings and integrate products. For example, VMware purchased Blue Lane Technologies and incorporated Blue Lane's software into its vShield product line. Juniper Networks purchased Altor Networks Virtual Firewall and is integrating Altor into its line of firewalls and management software. And Third Brigade is now part of Trend Micro's Deep Security line.

From InformationWeek's special digital supplement (PDF) March 2011:

Complexity is the enemy of security, and today's virtualized infrastructures are anything but simple. If your security policies haven't kept up, it's time to reassess. InformationWeek's special digital supplement can help.

Virtualization Security: Virtualized servers are still just servers. Stick with what you know. InformationWeek Analytics' Virtualization Security Survey analysis provides low-cost steps to keep data safe.

Hypervisor Security: New hypervisor hardening options.




Virtual PC top

Used to be a full-blown hypervisor that supported multiple different guest operating systems but support and functionality has declined ever since Microsoft bought the product from Connectix in 2003.

Nowadays essentially only supported on Windows 7 and with primary purpose to run the Windows XP mode in Windows 7. (Note that setting up all this is a rather time consuming task and we recommend spending this time on getting a more flexible solution.)

After years of use we no longer bother with Virtual PC (Windows Virtual PC) but focus on the big three above (Parallels, VMware, and VirtualBox).




Updated 2012-10-20