VM states (running, stopped, deallocated) in Azure - Deep Dive

Overview - VM states (running, stopped, deallocated)

What is it?

Virtual Machines (VMs) in Azure can be in different states that describe their current activity and resource usage. The main states are running, stopped, and deallocated. Running means the VM is active and using compute resources. Stopped means the VM is turned off but still reserving resources. Deallocated means the VM is turned off and not reserving resources, freeing them for others.

Why it matters

Knowing VM states helps control costs and manage resources efficiently. Without understanding these states, you might pay for unused resources or face unexpected downtime. For example, stopping a VM without deallocating it still incurs charges, while deallocating stops charges but requires time to restart.

Where it fits

Before learning VM states, you should understand what a Virtual Machine is and basic cloud resource management. After this, you can learn about scaling, automation, and cost optimization strategies in Azure.

Mental Model

Core Idea

A VM's state controls whether it is active, paused but reserved, or fully shut down and released, directly affecting resource use and cost.

Think of it like...

Think of a VM like a rented car: running is driving it, stopped is parking it but still paying the rental fee, and deallocated is returning the car so you stop paying.

┌───────────────┐      ┌───────────────┐      ┌───────────────┐
│   Running     │─────▶│   Stopped     │─────▶│ Deallocated   │
│ (Active VM)   │      │ (Off, reserved)│      │ (Off, freed)  │
└───────────────┘      └───────────────┘      └───────────────┘
       ▲                     │                      │
       │                     │                      │
       └─────────────────────┴──────────────────────┘

Build-Up - 6 Steps

1

Foundation

What is a Virtual Machine

Concept: Introduce the basic idea of a VM as a computer inside the cloud.

A Virtual Machine is like a computer you can use remotely. It has its own operating system and runs programs just like your laptop. In Azure, you create VMs to run applications without needing physical hardware.

Result

You understand that a VM is a cloud computer you can control remotely.

Understanding what a VM is sets the stage for learning how its state affects usage and cost.

2

Foundation

Basic VM Lifecycle States

Concept: Introduce the idea that VMs can be turned on or off, affecting their availability.

A VM can be running (on and ready), stopped (turned off but still reserved), or deallocated (turned off and resources released). These states control if the VM is usable and if you pay for it.

Result

You know the three main VM states and their basic meanings.

Knowing VM states helps you manage when your VM is active or not.

3

Intermediate

Running State Details and Costs

🤔Before reading on: Do you think a running VM uses compute resources and costs money continuously? Commit to your answer.

Concept: Explain what happens when a VM is running in Azure.

When a VM is running, it uses CPU, memory, and storage resources. Azure charges you for these resources every minute. The VM is fully operational and can respond to requests.

Result

You understand that running VMs consume resources and incur costs.

Understanding running state costs helps avoid unexpected charges by keeping VMs active only when needed.

4

Intermediate

Stopped State vs Deallocated State

🤔Before reading on: Does stopping a VM always stop all charges? Commit to your answer.

Concept: Clarify the difference between stopped and deallocated states.

Stopping a VM from inside the OS turns it off but keeps the hardware reserved, so you still pay for it. Deallocating a VM releases the hardware, stopping compute charges. You can stop a VM from Azure portal or CLI to deallocate it.

Result

You can distinguish stopped (still paying) from deallocated (not paying) states.

Knowing this difference prevents paying for unused resources and helps control cloud costs.

5

Advanced

How Azure Manages VM Resources

🤔Before reading on: Do you think deallocated VMs lose their data? Commit to your answer.

Concept: Explain resource reservation and data persistence in VM states.

When a VM is deallocated, Azure releases compute resources but keeps the VM's disk data intact in storage. This means your data is safe, but the VM needs time to start again. Stopped VMs keep compute reserved, so they start faster but cost more.

Result

You understand resource management and data safety across VM states.

Knowing resource and data handling helps balance cost and performance needs.

6

Expert

Impact of VM States on Automation and Scaling

🤔Before reading on: Can automation scripts safely deallocate VMs to save costs without losing data? Commit to your answer.

Concept: Explore how VM states affect automated workflows and scaling strategies.

Automation tools can stop or deallocate VMs to save costs during low demand. Deallocating is preferred to avoid charges but requires handling startup delays. Scaling solutions consider VM states to optimize resource use and cost dynamically.

Result

You see how VM states integrate with real-world automation and scaling.

Understanding VM states deeply enables smarter automation and cost-efficient scaling in production.

Under the Hood

Azure manages VMs by allocating physical hardware resources like CPU and memory when a VM is running. When stopped but not deallocated, the hardware remains reserved but powered off. Deallocation releases hardware back to the pool. VM disks are stored separately in durable storage, preserving data regardless of VM state.

Why designed this way?

This design balances cost, performance, and data safety. Keeping hardware reserved for stopped VMs allows quick restart but costs more. Deallocation frees resources to optimize cloud efficiency. Separating disk storage ensures data persistence independent of compute state.

┌───────────────┐       ┌───────────────┐       ┌───────────────┐
│   Running     │──────▶│   Stopped     │──────▶│ Deallocated   │
│ (Hardware ON) │       │ (Hardware OFF)│       │ (Hardware FREE)│
└───────┬───────┘       └───────┬───────┘       └───────┬───────┘
        │                       │                       │
        │                       │                       │
        ▼                       ▼                       ▼
  ┌───────────┐           ┌───────────┐           ┌───────────┐
  │  Disk     │           │  Disk     │           │  Disk     │
  │ Storage   │           │ Storage   │           │ Storage   │
  └───────────┘           └───────────┘           └───────────┘

Myth Busters - 4 Common Misconceptions

Quick: Does stopping a VM from inside the OS stop all Azure charges? Commit to yes or no.

Common Belief: Stopping a VM inside the operating system stops all charges immediately.

Reality: Stopping a VM inside the OS only powers it off but does not deallocate resources, so compute charges continue.

Why it matters: This misconception leads to unexpected costs because users think their VM is fully off when it is not.

Quick: Can deallocating a VM cause loss of data on the VM's disk? Commit to yes or no.

Common Belief: Deallocating a VM deletes all data on its disks.

Reality: Deallocating a VM releases compute resources but preserves all disk data in Azure Storage.

Why it matters: Fear of data loss may prevent users from deallocating VMs and saving costs.

Quick: Does a stopped VM start instantly like a running VM? Commit to yes or no.

Common Belief: Stopped VMs start instantly because hardware is reserved.

Reality: Only stopped (not deallocated) VMs start quickly; deallocated VMs require resource allocation and take longer to start.

Why it matters: Misunderstanding startup times can cause delays in production environments.

Quick: Is the stopped state the same as deallocated in terms of billing? Commit to yes or no.

Common Belief: Stopped and deallocated states are the same for billing purposes.

Reality: Stopped VMs still incur compute charges; deallocated VMs do not.

Why it matters: Confusing these states can lead to higher cloud bills.

Expert Zone

1

Azure's internal scheduler optimizes resource allocation dynamically, so deallocated VMs may be assigned different hardware on restart, affecting performance consistency.

2

Some VM extensions or features may behave differently or require reconfiguration after deallocation and restart.

3

Azure's billing granularity is per minute, so short stop/start cycles may still incur charges; understanding this helps optimize automation scripts.

When NOT to use

Avoid relying solely on stopping VMs to save costs in production; use deallocation instead. For ultra-low latency needs, consider reserved instances or dedicated hosts to avoid startup delays. For ephemeral workloads, consider container services instead of VMs.

Production Patterns

In production, teams automate VM deallocation during off-hours to save costs, using Azure Automation or DevOps pipelines. They monitor VM states to trigger alerts if VMs remain running unexpectedly. Scaling solutions integrate VM state checks to optimize resource use dynamically.

Connections

Cloud Cost Management

VM states directly influence cloud billing and cost optimization strategies.

Understanding VM states is essential to control cloud spending and avoid surprise bills.

Infrastructure as Code (IaC)

IaC tools manage VM states declaratively to automate lifecycle and cost control.

Knowing VM states helps write effective IaC scripts that handle start, stop, and deallocate actions properly.

Operating System Power States

VM states conceptually relate to OS power states like sleep, hibernate, and shutdown but differ in resource management.

Comparing VM states to OS power states clarifies why cloud resource billing depends on VM state, unlike local computers.

Common Pitfalls

#1 Stopping a VM inside the OS to save costs but forgetting it still incurs charges.

Wrong approach:

ssh into VM
sudo shutdown now
# VM is stopped but not deallocated

Correct approach:

az vm deallocate --resource-group MyGroup --name MyVM
# VM is stopped and deallocated, stopping compute charges

Root cause:

Confusing OS shutdown with Azure deallocation leads to unexpected billing.

#2 Assuming deallocating a VM deletes all data and not backing up disks.

Wrong approach:

az vm deallocate --resource-group MyGroup --name MyVM
# User deletes VM disks thinking data is lost

Correct approach:

az vm deallocate --resource-group MyGroup --name MyVM
# Data remains safe on disks stored separately

Root cause:

Misunderstanding Azure storage separation causes unnecessary data backup or fear.

#3 Automating VM stop/start without considering startup delays after deallocation.

Wrong approach:

Automate stop and immediate start expecting instant availability

Correct approach:

Automate deallocate during off-hours and schedule start with buffer time for startup

Root cause:

Ignoring VM startup time after deallocation causes automation failures or downtime.

Key Takeaways

Azure VM states control whether a VM is active, paused but reserved, or fully shut down and released.

Running VMs consume compute resources and incur charges continuously.

Stopped VMs are powered off but still reserve hardware, so charges continue.

Deallocated VMs release hardware resources, stopping compute charges but preserving disk data.

Understanding these states helps optimize cloud costs, manage resources, and design effective automation.