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I never use virtual machine before.

I plan to partition my hard drive (250GB) on a Thinkpad T400 laptop (8GB main memory, and install Ubuntu 14.04 as my main and host OS.

In the future, when I have to use some Windows software (such as Adobe Acrobat, MS Office, SAS), I will install a virtualization software program such as Virtualbox, KVM or VMWare Player, and then install and run Windows 7, 8.1 or 10 as a guest OS.

Since I now plan to partition my disk, I want to leave enough space for virtual machine and guest OS (even though I might not need them now), and have some questions:

  • In what partitions will the virtualization software program, and the guest OS be installed respectively?

  • If not considering what software applications which I will install and run under the guest Windows, how much space should I give for the guest OS and the virtualization software

  • if considering the software applications which I will install and run under the guest Windows, are the sizes taken by them similar to the sizes when they are installed under a Windows installed directly on a computer? E.g. will MS Office take up the same size when it is installed on a guest Windows as it is directly on a host Windows?

Thanks.

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  1. A guest OS of a virtual machine is a set of files and those file can be stored anywhere on your computer, including in your Ubuntu partition. By default VirtualBox stores the files of the guest OS in your user subfolder of your /home folder.

  2. The recommended size of the virtual hard drive for a either a Windows 7 guest OS or a Windows 8.1 guest OS in VirtualBox is 25.00 GB. The recommended size of the virtual hard drive for a Windows 10 Technical Preview guest OS in VirtualBox is 20.00 GB, although the recommended size of the Windows 10 virtual hard drive may change when Windows 10 is officially released.

    When you create the virtual hard drive, you can choose whether the new virtual hard drive should grow as it is used (dynamically allocated) or if it should be created at its maximum size (fixed size). A dynamically allocated hard drive file will only use space on your physical hard drive as it fills up (up to a maximum fixed size), although it will not shrink again automatically when space on it is freed.

  3. The space taken by an application in a guest OS running in a virtual machine is the same as the space that would be taken by that application if it was installed in the same operating system running in a physical machine.

  • Thanks. Are all the files for the guest Windows and for all software installed under the guest Windows located in the virtual hard drive? 8GB is too small to install a guest Windows alone. – Tim Feb 14 '15 at 3:32
  • Thanks. (1) Is it possible to specify the virtual drive to be on an external hard disk? (2) by the way, the virtual hard drive is used for storing guest OS and software installed in the guest OS, not for anything else including the virtualization software e.g. VirtualBox? – Tim Feb 14 '15 at 3:48
  • 1. The virtual hard drive can be created anywhere on the filesystem, preferably in a folder where you have the normal user permissions to read/write/execute files, including on an external hard drive. 2. Each guest OS in VirtualBox has its own separate folder containing the files of that guest OS, and the rest of the files of the VirtualBox application itself are not stored in that folder. – karel Feb 14 '15 at 4:04
  • Is VirtualBox itself taking 8GB or so? and must it be under /? – Tim Feb 14 '15 at 4:28
  • The VirtualBox application takes up about 130MB when installed. For the purpose of runnning Microsoft Office, Adobe Acrobat and SAS, you will be better off downloading VirtualBox from the official Oracle website, rather than installing it from the Ubuntu Software Center. VirtualBox from the official Oracle website has more features (fullscreen, shared folders, support for removable USB drives), so its installed size is probably a bit larger than 130MB. By the way, SAS will not run properly in Wine (Microsoft Windows Compatibility Layer) in Ubuntu. – karel Feb 14 '15 at 4:40
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In what partitions will the virtualization software program, and the guest OS be installed respectively?

All virtualization software can use ordinary files and that is usually preferred for its simplicity but using allocated partitions/volumes is a bit faster. Virtualbox and KVM support LVM (VMware probably as well). To use LVM, you would set one partition for the whole disk, create LVM group inside it and create a LVM volume (not using the whole group) for your host system. New volumes can be then created, resized or removed when needed.

If not considering what software applications which I will install and run under the guest Windows, how much space should I give for the guest OS and the virtualization software

The virtualization software will not use any space from the disk allocated to the guest. For space requirements of the guest OS, consult the guest's official system requirements. It will be the same as when installed on a physical computer.

if considering the software applications which I will install and run under the guest Windows, are the sizes taken by them similar to the sizes when they are installed under a Windows installed directly on a computer? E.g. will MS Office take up the same size when it is installed on a guest Windows as it is directly on a host Windows?

Yes, for the applications the system behaves just the same as on a physical computer so they will use the same amount of space.

  • thanks. (1) by "using allocated partitions/volumes is a bit faster", do you mean a dedicated partition/volume for the guest OS? (2) "To use LVM, you would set one partition for the whole disk", do you mean not separate swap, /home, and / into different partitions? – Tim Feb 14 '15 at 3:30
  • (1) Yes (2) You can create swap, /home and / as separate volumes inside the LVM group – StenSoft Feb 14 '15 at 3:31
  • (2) I never use LVM before. How is that done? When I install host Ubuntu, I think Ubuntu will use gparted to aid me through partitioning? How can I use LVM? – Tim Feb 14 '15 at 3:34
  • Both gparted and Ubuntu installer support LVM. You can read some information about it in Ubuntu Wiki. The creation is very similar to ordinary partitions but everything else (resize, remove, move or even snapshot or clone) is much easier. – StenSoft Feb 14 '15 at 3:38

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