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I work as a software consultant who works primarily in the windows environment. My laptop is my lifeline and I can ill-afford any downtime if it goes belly up. Somebody suggested running windows in a virtual machine in Ubuntu, and should my primary laptop goes down, take the VM file to my backup machine and viola! I am in business.

But a lot of posts about the setup I am looking at point to significant performance degradation which I can't afford with a memory hog that is Visual Studio.

I am open to ideas.

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closed as off topic by Jjed, Jorge Castro, izx, SirCharlo, ajmitch Aug 22 '12 at 3:18

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So what's your question? What do you mean if the "laptop goes belly-up"? Screw up the OS or break the actual machine? – netcoder Jul 25 '12 at 20:53
I don't think this actually is a question... if you want advice, I recommend a sensible online backup of critical projects/documents. Then you can reinstall an OS or buy a new laptop without losing anything. – Jjed Jul 26 '12 at 10:43

3 Answers 3

Years ago I did some benchmarking and in my tests tasks ran about 30% slower in a VM than on a "bare hardware". I would expect things to only get better since then.

So, basically, if you can do you business on a laptop which is 30% slower and has a little less RAM than you'll be fine.

However, if you only do this for the reasons of backup, there's probably no need - it would probably take about the same amount of effort to set up Ubuntu on a separate partition to be able to boot into it and dump the whole Windows partition to another laptop. Whether Windows will boot on that laptop is another question, but it probably will if the machines are identical.

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Yes: it is easy to carry a virtual machine to anywhere (even to a different host operating system) provided you have a data carrier big enough to hold your virtual machine including all data stored there.

No: you will likely not be able to get hold of your virtual machine in case your laptop has a hardware defekt.

Only reliable solution: Backup your data frequently

Possibly: There are few situations where an OS residing in a virtual machine may be of advantage in the follwing cases:

  • Carry a system to another computer where it is not possible to restore backups (e.g. because we do not want to install the OS).
  • A highly customized OS where restoring and reinstalling may not be accomplished easily.
  • Small virtual machines that can be saved and restored in a sensible way.
  • Running an OS that can not easily be restored from backups on different hardware.

It may therefore be that when you are running a fairly customized Windows in a virtual machine it may indeed be faster to restore your working enivronment on different hardware.

In case you are not running applications that demand a poweful graphic card, and running the virtual machines on a host with enough RAM to spare for the virtual machine then you may not suffer from much loss of performance. Modern virtualalization solution are doing a very good job at this.

Note that incremental backups from your virtual machine can only be done from the virtual guest as the files on you virtual hard disk are stored in a single file on the host that will have been changed on every boot. For easier backups it may also be a good idea to save your data in a shared folder on the host machine. This will enable incremental backups and also will keep your virtual hard disks small.

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I think you misunderstood my question. I have no doubt the setup I am thinking of to keep my business afloat will work. I also know that the VM file will have to be backed up. My concern is performance degradation, and I am wondering if there is another solution that still achieves my objectives which are 1)way to use the backup in case my primary machine croaks 2)still have good performance. I see that VMware offers a way to create a VM file out of a physical machine. Is that a good way to go? – user79284 Jul 25 '12 at 21:19
@user79284: Edited some additional thoughts after having slept over it (yesterday I almost didnt remember how painful it was restoeing a Windows). – Takkat Jul 26 '12 at 6:18

If your laptop is only a couple of years old and has a CPU with hardware virtualization, then a virtual machine will run at almost 100% of the speed you'd get on the bare hardware.

Even if it doesn't (mine doesn't) most virtual machine software (I use VirtualBox) tries to execute as much as possible directly, so the difference is not usually noticeable.

If you want the technical summary, the VirtualBox documentation explains that, in the absence of virtualization hardware, the VM manager arranges for all 'user' code (CPU ring 3) to run as normal and for 'kernel' code (CPU ring 0) to run in CPU ring 1, which is not normally used. The effect is that most code runs at full speed. There's a slight overhead of running the virtual device drivers mapping the disk, display, etc, but most of the time it's minimal. I believe all other virtualization solutions on x86/x64 running on x86/x64 work in a similar manner.

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