First VM

Topic: Creating Your First Virtual Machine

1. The VM Creation Process

Creating a Virtual Machine (VM) involves defining a software-based computer specification. When you click "New" in VirtualBox, you aren't building a physical machine, but you are creating a configuration file (typically .vbox) that tells the hypervisor what hardware to emulate.

The Wizard Steps:

Name & OS Type: Naming the VM and selecting the target OS (e.g., Linux, Windows) helps the hypervisor apply optimal defaults.
Memory Size: Allocating RAM.
Hard Disk: Creating a virtual hard drive.

2. Allocating Virtual Hardware

Virtual CPU (vCPU)

By default, a new VM usually gets 1 vCPU. Modern hypervisors allow you to assign multiple cores.

Understanding vCPU vs. Core vs. Thread: To allocate resources correctly, you must understand the hierarchy of physical vs. virtual processing:

Physical Core: A physical independent execution unit on your CPU chip. Most mainstream laptops today have 4 to 8 physical cores.
Hardware Thread: Modern CPUs use Simultaneous Multithreading (SMT, or Intel's "Hyper-Threading"). This technology allows a single physical core to behave like two logical processors by keeping the core's execution units busy more of the time.
Logical Processor: A CPU with 4 cores and SMT/Hyper-Threading has 8 Logical Processors. This is what the operating system and hypervisor see.
vCPU (Virtual CPU): This is what the hypervisor presents to the VM. In most cases, 1 vCPU maps to 1 Logical Processor (Hardware Thread) on the host.

Constraint: You cannot assign more virtual cores than your physical host possesses. Always check your host's core count.

Hidden Hardware Features: PAE/NX

When you select an OS version in VirtualBox, it often enables these key features automatically:

PAE (Physical Address Extension): Allows 32-bit processors to access more than 4 GB of RAM.
NX (No-Execute) Bit: A security feature that helps prevent malicious code from executing in data-only memory areas (e.g., buffer overflow attacks). It's also called XD (Execute Disable) on Intel CPUs.

Virtual RAM

This is reserved from your physical host's memory.

Rule of Thumb: Never allocate more than 50-60% of your total host RAM to running VMs.
The Swap Warning: If you over-allocate RAM, your host will start "swapping" memory to the hard drive, causing extreme performance degradation (the "swap death spiral").

3. Virtual Hard Disks

A virtual disk is simply a large file on your host computer.

Common Formats:

VDI (VirtualBox Disk Image): The native format for VirtualBox.
VMDK (Virtual Machine Disk): Format used by VMware. Good for compatibility.
VHD/VHDX: Microsoft formats, useful for Hyper-V compatibility.

Allocation Types:

Dynamically Allocated: The file starts small and grows as you save data inside the VM. Saves space initially.
Fixed Size: The full size is reserved immediately. Better performance, but takes up all the space upfront.

4. Guest Operating Systems & ISO Images

A new VM is like a computer with a blank hard drive. We need to install an Operating System (Guest OS).

ISO Images: Digital replicas of installation discs.
Mounting: You "insert" the ISO file into the VM's virtual optical drive via storage settings.

5. Installing the Guest OS

Boot Order: The VM detects the bootable ISO in the virtual optical drive.
Installer: Follow the OS installer's prompts.
Post-Install: You must "eject" the ISO (unmount it) from settings so the VM boots from its virtual hard disk on the next restart.

6. Lab Exercises (TP/CC)

Download an ISO: Download the Lubuntu or Debian ISO image.
Create a New VM:
- Name: Lab1-Linux
- Type: Linux, Version: Ubuntu (64-bit) or Debian (64-bit)
- RAM: 2048 MB (2 GB)
- HDD: Create a new VDI, Dynamically Allocated, 20 GB.
Mount the ISO: Go to Settings > Storage, click the "Empty" CD icon, and select your ISO.
Install: Start the VM and follow the installer.
Verify: Shut down, remove the ISO, and reboot into your new virtual Linux desktop.

Less Common Use Case: Boot Parameter Interaction

Advanced Task: During the installation phase, interrupt the boot process (often by pressing a key like ESC or Shift during the initial load) and examine the boot parameters. For Linux installers, try appending a parameter like nomodeset or specifying an initial root filesystem to see how these parameters affect hardware detection during the initial boot sequence.