Run a Guest OS Alongside Apps in a VM

Running a guest operating system inside a virtual machine (VM) lets you use Windows, Linux, or another OS side-by-side with your main system’s apps, without rebooting. You get an isolated environment for testing software, trying new OS versions, or running incompatible programs. This guide covers the essential steps using free, mainstream virtualization tools like VirtualBox or VMware Workstation Player.

What You’ll Need

• A host computer with at least 8 GB of RAM (16 GB recommended) and a 64-bit CPU with virtualization enabled in the BIOS/UEFI (Intel VT-x or AMD-V).
• A virtualization program installed: Oracle VirtualBox (free) or VMware Workstation Player (free for personal use).
• An ISO image or installation disc of the guest OS you want to run (e.g., Ubuntu, Windows 10/11, Linux Mint).
• Enough free disk space: 20–50 GB for the virtual hard drive, depending on the guest OS.
• Administrator access on the host to install the software and enable virtualization.

Step-by-Step

1. Enable virtualization in BIOS/UEFI. Restart your computer, enter the BIOS/UEFI setup (usually by pressing Del, F2, or F10 during boot), find the CPU or Advanced settings, and enable Intel VT-x or AMD-V. Save and exit. This is required for 64-bit guests and good performance.
2. Install the virtualization software. Download and install VirtualBox or VMware Workstation Player from the official website. Follow the installer prompts; accept the default options unless you have a reason to change them.
3. Download the guest OS ISO. Get the installation image of the OS you want to run. For Linux distributions, the official websites offer free ISO files. For Windows, use the official media creation tool or ISO download page.
4. Create a new virtual machine. Open the virtualization software, click “New” (VirtualBox) or “Create a New Virtual Machine” (VMware). Give the VM a name and choose the guest OS type and version from the dropdown lists.
5. Allocate memory (RAM). Set the amount of RAM for the guest. A safe starting point is 2–4 GB for a desktop Linux or Windows 10/11. Do not allocate more than half of your host’s total RAM, or the host may become sluggish.
6. Create a virtual hard disk. Choose “Create a virtual hard disk now” and select the disk type (VDI for VirtualBox, VMDK for VMware). Pick “Dynamically allocated” so the file grows as you use space. Set the size to 25–50 GB.
7. Configure the VM settings (optional but recommended). In the VM settings, increase video memory to 128 MB, enable 3D acceleration if the guest needs it, and set the number of CPU cores to 2 or more if your host has spare cores.
8. Attach the ISO file. In the VM settings, go to Storage (VirtualBox) or CD/DVD (VMware), and attach the ISO file as a virtual optical disc. Make sure the optical drive is set to boot first in the boot order.
9. Start the VM and install the guest OS. Click “Start”. The VM will boot from the ISO. Follow the on-screen installer just as you would on a physical computer. Choose the virtual disk as the installation target (it will show as an empty disk).
10. Install guest additions (recommended). After the guest OS is installed and running, install the guest additions (VirtualBox) or VMware Tools. This provides better screen resolution, mouse integration, and clipboard sharing. In the VM menu, select “Devices” > “Insert Guest Additions CD image” (VirtualBox) or “VM” > “Install VMware Tools” (VMware), then run the installer inside the guest.
11. Run the guest alongside host apps. Once installed, you can start the VM from the main program window whenever you need it. The guest runs in a window on your desktop, and you can switch between the guest and your host apps freely. You can also enable seamless mode (VirtualBox) or unity mode (VMware) to show guest app windows directly on the host desktop.

Common Mistakes

• Forgetting to enable virtualization in BIOS – the VM may run very slowly or fail to start 64-bit guests.
• Allocating too much RAM to the guest, leaving the host without enough memory and causing system sluggishness.
• Choosing a fixed-size virtual disk when you are short on space – dynamic disks are more flexible.
• Not installing guest additions, resulting in poor screen resolution and no clipboard sharing.
• Attaching the ISO but forgetting to remove it after installation – the VM may try to boot from it again.

Tips

• Use snapshots before major changes inside the guest – you can revert to a clean state instantly.
• For better performance, place the virtual disk on an SSD rather than a mechanical hard drive.
• If you need to transfer files between host and guest, set up shared folders in the VM settings (requires guest additions).
• Keep the guest OS updated with the latest security patches, just like a physical machine.
• If the guest is only for testing, consider using a lightweight Linux distribution to save resources.

Troubleshooting

• VM won’t start or shows “VT-x is not available”: Reboot, enter BIOS, and enable virtualization. Also check if Hyper-V is enabled on Windows – you may need to disable it in Windows Features or use a VM tool that supports Hyper-V.
• Guest OS runs extremely slowly: Increase RAM and CPU cores in VM settings, ensure virtualization is on, and install guest additions. Also close heavy host applications while the VM runs.
• Screen resolution is stuck at 800×600: Install guest additions or VMware Tools – this is the most common cause.
• Cannot drag and drop files between host and guest: Enable shared folders or drag-and-drop in VM settings, and ensure guest additions are installed.
• Guest OS doesn’t see the virtual disk during installation: Make sure you selected the virtual disk as the installation target, not a physical disk. In some cases, you need to format the virtual disk first in the installer.
• Network doesn’t work in the guest: In VM settings, set network adapter to NAT (default) – this usually works out of the box. If not, try bridged mode.

Frequently Asked Questions

1. Can I run a 32-bit guest on a 64-bit host? Yes, most virtualization software supports 32-bit guests even on 64-bit hosts, as long as virtualization is enabled.
2. How much RAM should I give the guest? Start with 2–4 GB for desktop OSes. The guest needs enough to run smoothly, but the host must have enough left over.
3. Will the guest OS affect my host files? No, the guest runs in a sandboxed environment. It can only access host files if you explicitly set up shared folders or network shares.
4. Can I run multiple VMs at the same time? Yes, but each VM consumes CPU, RAM, and disk I/O. Ensure your host has enough resources for all of them.
5. Is it safe to test malware in a VM? It’s safer than testing on your host, but not completely isolated – use snapshots and avoid shared folders if you’re concerned.
6. Do I need a separate license for the guest OS? Yes, if the guest OS is commercial (like Windows), you need a valid license. Free Linux distributions don’t require one.

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