How Virtualization Tried To Solve Deployment Issues

Before containers became popular, virtual machines were the common way to isolate applications and make server usage more efficient.

Virtualization was a big improvement. It allowed one physical machine to run multiple virtual machines, and each virtual machine could have its own operating system, software, configuration, and application.

That helped teams avoid many conflicts. But it also introduced extra weight.

What a virtual machine is

A virtual machine is a complete computer running inside another computer.

It has:

• A virtual CPU
• Virtual memory
• Virtual disk
• A full guest operating system
• Application runtime and dependencies
• The application itself

This is possible because of a layer called a hypervisor. The hypervisor sits between the physical hardware and the virtual machines, sharing the real machine's resources across multiple isolated systems.

Physical hardware
-> Host operating system
-> Hypervisor
-> Guest operating system
-> Runtime and dependencies
-> Application

Each virtual machine behaves like a separate server.

What virtualization solved

Virtual machines helped with some important problems.

Earlier, companies often ran one application on one physical server. That wasted resources because many servers used only a small part of their CPU and memory. Virtual machines allowed multiple applications to run on the same physical hardware while still staying isolated from each other.

Virtualization gave teams:

• Better hardware usage
• Isolation between applications
• Easier server creation
• Separate environments for different teams
• A more predictable setup than random manual installation

This was a major step forward.

Where virtual machines became heavy

The problem is that every virtual machine carries a full operating system.

If you run five virtual machines, you may also be running five guest operating systems. That means more disk usage, more memory usage, slower startup, and more patching.

Virtual machines are powerful, but they are not always the fastest or lightest way to package an application.

The deployment problem still existed

Virtual machines improved isolation, but they did not completely remove environment complexity.

Someone still had to prepare the VM:

• Install the correct runtime
• Install dependencies
• Copy application files
• Configure environment variables
• Open ports
• Start services
• Maintain OS updates

If this setup was done manually, the same old problem returned. Two VMs could still become different over time.

This is called configuration drift. It happens when servers slowly change because of manual fixes, patches, and one-time commands.

Why containers became attractive

Containers kept the useful idea of isolation but removed much of the heavy operating-system duplication.

Instead of packaging a full guest OS for every application, containers share the host machine's kernel and package only what the application needs above that level.

Virtual machine
app + runtime + guest OS

Container
app + runtime + dependencies

This difference is the reason containers usually start faster and use fewer resources.

Virtual machines are still useful, especially in cloud platforms like AWS EC2. But for packaging and running applications quickly, containers became the more lightweight solution.

Written By: Shiva Srivastava