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Introduction to Azure virtual machines | AZ-104 | Episode 20

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Cloud service models and IaaS

  1. The module introduces Azure Virtual Machines as Infrastructure as a Service, contrasting IaaS with PaaS and SaaS in the cloud shared-responsibility model.
  2. Microsoft takes responsibility for much of the physical infrastructure, while administrators still manage the virtual machines and workloads they deploy.
  3. The presenter describes a migration example where many applications moved from VMs to PaaS, while remaining workloads moved to Azure IaaS to reduce hardware ownership and capital expense.

Azure VM capacity and sizing

  1. Azure VMs are globally available and range from very small sizes to extremely large machines with hundreds of cores and terabytes of RAM.
  2. VMs can be scaled up or down when requirements change, but resizing causes a reboot and should be planned carefully for production workloads.
  3. Availability of VM SKUs varies by Azure region, with larger regions such as East US typically offering more options first.
  4. You pay for VM compute, memory, and networking only while allocated, but storage costs continue even when the VM is stopped or deallocated.

VM storage structure

  1. A virtual machine is built from compute, memory, storage, and networking resources, with OS disks backed by VHD or VHDX files stored in Azure Storage.
  2. Azure Storage stores VM disk data multiple times, so VM disks benefit from Azure Storage durability characteristics.
  3. The temporary D drive is ephemeral and should not be used for persistent files because its contents are not reliable across lifecycle events.
  4. Additional data disks can be attached to VMs, and high-performance disk types such as Ultra Disk can be used for workloads like SQL data, tempdb, and logs.

Administration and secure access

  1. Directly logging into VMs through RDP or SSH is discouraged because it requires exposing management ports such as 3389 or 22.
  2. Azure Bastion provides a more secure access pattern by allowing administrators to connect over HTTPS and then reach VMs inside peered virtual networks without exposing public access to each VM.
  3. Bastion can function similarly to a jump box and is recommended for remote desktop access when that access is required.

Creating and managing VMs

  1. The Azure portal VM creation flow includes selecting a subscription, resource group, region, image, size, credentials, inbound port rules, licensing, disks, networking, and management settings.
  2. Microsoft provides supported Windows and Linux marketplace images, but organizations can also create custom images for unsupported or specialized operating systems.
  3. Networking choices include virtual network, subnet, public IP, and load balancer configuration, with public IP exposure generally discouraged for back-end VMs.
  4. Management options include shutdown scheduling, automation, Entra ID integration, and monitoring integration through Azure Monitor.
  5. Azure Monitor sees VM-level metrics such as CPU use, but guest-level process details require logs and metrics emitted from inside the VM.

Availability and self-healing

  1. Existing VMs may have limited options to be added to availability features after creation, but support varies by feature and has changed over time.
  2. Azure Resource Manager coordinates resource providers for compute, memory, networking, and storage when deploying a VM.
  3. If a storage copy or host node fails, Azure can self-heal the VM by redeploying it on another node and reconnecting its disks, typically after a short outage.
  4. Azure stores disk copies across fault domains so a VM can recover from node or fault-domain failures, but broader failures require high-availability designs covered in later modules.

Key takeaway

  1. Azure Virtual Machines provide traditional VM capability while shifting major physical infrastructure, availability, security, and scaling responsibilities to Microsoft.
  2. Azure offers broad VM size choices that can be resized to match changing workload needs without waiting for new hardware procurement.

Actiepunten

  1. Do not store persistent files on the ephemeral D drive.
  2. Use Azure Bastion instead of directly exposing RDP or SSH to virtual machines when remote access is needed.
  3. Review Azure VM storage best practices when choosing OS disks, data disks, and high-performance disk placement.
  4. Use templates, PowerShell, CLI, or automation when repeatable VM deployment and lifecycle management are needed.