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I need to build a portable virtual machine that could be used on user restricted PCs that need admin permissions. I've heard about QEMU. But the problem is that it is very very slow when running. Is there a high performance alternative? I'm thinking of the ability to control the boot menu temporary without admin privileges, and boot up my custom virtual disk image as a solution if it is possible, but I don't know.

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    Lack of admin rights, and portability are orthogonal. You need low level hardware access for high performance virtualisation. qemu gets around this by emulating an entire system. If you're somewhere with restricted user rights, its generally for a reason.
    – Journeyman Geek
    Oct 4, 2014 at 2:34
  • I've tried QEMU before, but it was too small. Do you have any idea how to bootload my custom system image on an external FDD? knowing that I don't have an access to the BIOS setup as it is password protected.
    – Omar
    Oct 5, 2014 at 3:03

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Without admin privileges on the Host OS it will be very difficult to get high performance from your Guest OS unless the system was already pre set up to let you start your portable VM image as a non administrator. For example if VMWare player was already pre-installed on a machine you could easily move your VM on and off the machine making it portable, and you don't need admin privileges to add or remove the VM from the player software.

If there is no VM software already installed in the Host OS you will need to replace the Host OS. This can be easily done without making any modifications to the computer if the computer you are using supports booting from USB or the CD/DVD drive. What you will need to do is make a Live CD/USB with VirtualBox or other similar Linux VM host software pre-installed on it and also have your VM on a portable USB drive (it can even be the same drive that you are booting from). You then you just need to reboot the computer you want use and boot in to your Live CD/USB and start up your VM, you will be the "administrator" of Live CD/DVD's OS so the VM software can use the low level drivers that will get you good performance inside your VM.

Your biggest limiting factor in both setups will be the read and write speed of the USB drive you put your VM image on. Most cheap USB sticks do not have good write performance and I would recommend paying for a higher end one that lists good write speeds or even put it on a portable external SSD.

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  • Do you have any idea how to bootload my custom system image on an external media? knowing that I don't have an access to the BIOS setup as it is password protected.
    – Omar
    Oct 5, 2014 at 3:04
  • If the BIOS is not set up to boot from external media there is nothing you can do. All you can do is ask the system administrator to install the software to run your own VMs you provide. Oct 5, 2014 at 3:38
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Qemu is high in performance. You just need to increase the amount of virtual processes. Use the -smp command line thingy to set the number of processors. Example -smp 4 would emulate 4 processors.

NOTE: Qemu has said that the 1 virtual processor does not necessarily equal 1 real processor so it would use the full processor if you use 5 or 6 cores depending on your processor speed.

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