Azure Virtual Machines (VMs)

Overview

Azure Virtual Machines are on-demand, scalable computing resources that provide full control over the operating system, storage, and networking. They are ideal when you need more flexibility than Platform as a Service (PaaS) offerings like Azure App Service.

Azure VMs are part of Infrastructure as a Service (IaaS), where computing infrastructure is provisioned over the internet and billed based on usage.

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IaaS Business Scenarios

Azure Virtual Machines are commonly used for:

• Test and Development

  • Rapid provisioning and teardown of environments

  • Cost-effective scaling for dev/test workloads

• Website Hosting

  • Often more economical than traditional hosting

  • Full control over server configuration

• Storage, Backup, and Disaster Recovery

  • No capital investment in hardware

  • Simplified backup and compliance management

• High-Performance Computing (HPC)

  • Used for simulations, modeling, and scientific workloads

  • Examples: climate modeling, protein folding, financial analysis

• Big Data Analytics

  • Supports massive datasets requiring high processing power

• Extended Datacenter

  • Add capacity without expanding physical infrastructure

  • Seamless connectivity with on-premises networks

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Virtual Machine Planning Checklist

Before provisioning a VM, consider:

1. Network configuration

2. VM naming conventions

3. Deployment location (region)

4. VM size selection

5. Pricing model

6. Storage requirements

7. Operating system selection

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Start with the Network

• Azure VMs connect through Virtual Networks (VNets)

• Resources in the same VNet can communicate privately

• External access (internet or on-premises) must be explicitly configured

• Network address ranges and subnets are difficult to change later, so plan carefully

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Naming the VM

VM names:

• Become the OS computer name

• Are difficult to change after deployment

• Max length:

  • Windows: 15 characters

  • Linux: 64 characters

Recommended naming elements:

Example: devusc-webvm01

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Location and Pricing Considerations

When choosing a region:

• Place VMs close to users for better performance

• Meet legal, compliance, or data residency requirements

• Be aware:

  • Not all VM sizes are available in every region

  • Prices vary between regions

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Azure VM Pricing Model

Azure VM costs consist of two independent charges:

1. Compute Costs

• Billed per minute

• Charged only when VM is running

• No compute charge when VM is stopped and deallocated

• Windows VMs include OS licensing

• Linux VMs are cheaper (no license cost)

Compute pricing options:

• Consumption-based (Pay-as-you-go)

  • Ideal for short-term or unpredictable workloads

• Reserved VM Instances (1 or 3 years)

  • Up to 72% savings

  • Best for always-on workloads and predictable budgets

2. Storage Costs

• Charged regardless of VM state

• Applies even when VM is stopped

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Virtual Machine Sizing

Azure offers predefined VM sizes optimized for different workloads:

VM Categories

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Resizing Virtual Machines

• VM sizes can be changed as workload needs evolve

• Some resizing requires:

  • VM reboot

  • Temporary downtime

  • Possible IP address change

• Stopping and deallocating a VM allows access to all available sizes in the region

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Virtual Machine Disks

Every Azure VM includes:

Operating System Disk

• Pre-installed OS

• Max size: 2,048 GiB

• Appears as:

  • Windows: C: drive

• Uses SATA interface

Temporary Disk

• Not managed

• Used for swap/page files only

• Data may be lost during maintenance or redeployment

• Appears as:

  • Windows: D: drive

  • Linux: /dev/sdb mounted to /mnt

⚠️ Do not store critical data on the temporary disk

Data Disks

• Managed disks used for persistent data

• Max size per disk: 4,095 GiB

• Attached as SCSI disks

• Number depends on VM size

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Azure Disk Storage Options

Managed Disks (Recommended)

• Azure handles storage accounts and availability

• Disk types:

  • Ultra SSD

  • Premium SSD

  • Standard SSD

  • Standard HDD

• Required for 99.95% SLA on single-instance VMs

Unmanaged Disks

• Legacy approach

• Customer manages storage accounts and VHD files

• Not recommended for new deployments

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Performance and Storage Guidance

• Use Premium SSD or Ultra SSD for high IOPS workloads

• Use Standard HDD/SSD for cost savings when performance is not critical

• Premium Storage supports:

  • Up to 80,000 IOPS per VM

  • Up to 2,000 MB/s throughput