Understanding VMware and Virtualization - Part 2

What Is VMware ESXi?

VMware ESXi is a Type 1, or bare-metal, hypervisor.

It is installed directly on a physical server.

Physical Server
↓
ESXi
↓
┌────┼────┐
↓ ↓ ↓
VM1 VM2 VM3

ESXi provides the virtualization layer.

It allows multiple VMs to share the physical resources of the server.

For example, imagine a physical server has:

CPU: 32 cores
RAM: 128 GB
Storage: 2 TB

ESXi can host multiple VMs on that server.

Each VM can be assigned a certain amount of CPU, memory, storage, and network connectivity.

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How Does VMware Virtualization Work?

Let's understand the complete flow.

Step 1: Physical Server

First, we have a physical server containing hardware resources.

CPU
RAM
Storage
Network
Step 2: Install ESXi

ESXi is installed directly on the physical server.

Physical Hardware
↓
ESXi
Step 3: Create Virtual Machines

The administrator creates VMs on the ESXi host.

ESXi
├── VM1
├── VM2
└── VM3
Step 4: Assign Resources

Each VM receives virtual resources.

For example:

VM1 → 4 vCPU + 8 GB RAM
VM2 → 2 vCPU + 4 GB RAM
VM3 → 4 vCPU + 16 GB RAM
Step 5: Install Operating Systems

Each VM can have a supported operating system.

VM1 → Windows
VM2 → Linux
VM3 → Linux
Step 6: Run Applications

Applications are installed inside the guest operating systems.

The result is multiple independent workloads running on the same physical server.

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What Is a VMware Host?

A host is a physical server running ESXi.

For example:

Physical Server
↓
ESXi
↓
Host
↓
VMs

A large enterprise environment may contain many ESXi hosts.

For example:

ESXi Host 1
ESXi Host 2
ESXi Host 3
ESXi Host 4

These hosts can be managed together.

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What Is vCenter Server?

When an organization has many ESXi hosts, managing each host individually can become difficult.

This is where vCenter Server is used.

vCenter provides centralized management for VMware infrastructure.

            vCenter
               ↓
    ┌──────────┼──────────┐
    ↓          ↓          ↓
 ESXi 1     ESXi 2     ESXi 3
    ↓          ↓          ↓
   VMs        VMs        VMs

Through vCenter, administrators can manage resources and perform operations across supported VMware infrastructure.

For a beginner, remember:

ESXi runs the VMs. vCenter manages the VMware environment centrally.

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What Is VMware vSphere?

vSphere is VMware's server virtualization platform.

It brings together the technologies used to create and manage virtualized infrastructure.

A simplified view is:

vSphere
│
├── ESXi
│
└── vCenter

It is important not to confuse these terms.

ESXi is the hypervisor.

vCenter provides centralized management.

vSphere refers broadly to the VMware virtualization platform.

Exact product packaging and licensing can vary by VMware/Broadcom product version, so beginners should always check the documentation for the specific version they are learning.