Azure Managed Disks Overview

Azure Managed Disks is a foundational service for Azure Virtual Machines. It simplifies disk management and provides high availability, durability, and scalability for your VM workloads. Managed Disks handle the storage account management, encryption, and replication, allowing you to focus on your applications.

Key Benefit: Managed Disks abstract away the complexity of managing storage accounts for your virtual machines, significantly reducing operational overhead.

What are Managed Disks?

Managed Disks are block-level storage volumes that Azure manages for you. They are used as the underlying storage for virtual machines. Unlike unmanaged disks, where you had to manage the storage accounts and VHD files yourself, Managed Disks handle availability, durability, and scalability automatically.

Components of Managed Disks:

Disk Resource: A top-level Azure resource representing the virtual disk. It can be attached to a virtual machine.
Underlying Storage: Azure manages the physical storage for your disks, ensuring durability and availability.
Availability Sets & Zones: Managed Disks are designed to work seamlessly with Azure Availability Sets and Availability Zones for high availability.

Types of Managed Disks

Azure offers several types of Managed Disks to suit different performance and cost requirements:

Ultra Disks: Offer the highest performance with low, consistent latency. Ideal for I/O-intensive workloads like large relational databases, ERP, CRM, and data warehousing.
Premium SSDs (Solid State Drives): Provide high performance, low latency disk support for I/O-intensive workloads. Suitable for production and development/test environments.
Standard SSDs: Offer a cost-effective solution for workloads that require consistent latency at an even lower cost point than Premium SSDs. Good for web servers, lightly used applications, and development/test environments.
Standard HDDs (Hard Disk Drives): The most cost-effective option for non-critical, sequential I/O workloads. Suitable for backup, non-business-critical applications, and large-scale, infrequent access.

Conceptual comparison of Managed Disk performance characteristics.

Key Features and Benefits

Simplified Management: No need to manage storage accounts, VHDs, or underlying infrastructure.
High Availability: Managed Disks offer 99.999% availability through replication across multiple servers in a storage scale unit.
Durability: Data is durably stored with LRS (Locally Redundant Storage) or ZRS (Zone-Redundant Storage) options.
Scalability: Easily scale disk size and performance up or down as your needs change.
Encryption: Azure Disk Encryption (ADE) provides full disk encryption for OS and data disks, both at rest and in transit.
Snapshots and Images: Create point-in-time snapshots for backup and disaster recovery, or create custom images for deploying identical VMs.

How Managed Disks Work

When you create a virtual machine with Managed Disks, Azure automatically creates the necessary disk resources (OS disk and data disks) and manages their placement and replication within Azure storage. You interact with these disks through the Azure portal, Azure CLI, PowerShell, or ARM templates, specifying attributes like disk type, size, and performance tiers.


# Example: Creating a VM with Managed Disks using Azure CLI
az vm create \
  --resource-group MyResourceGroup \
  --name MyVM \
  --image UbuntuLTS \
  --admin-username azureuser \
  --admin-password 'YourPassword123' \
  --data-disk-sizes-gb 100 200 \
  --storage-sku Premium_LRS

Tip: For production workloads, consider using Premium SSDs or Ultra Disks for optimal performance and reliability. Always configure Availability Sets or Availability Zones for your VMs to ensure high availability.

Use Cases

Hosting databases (SQL Server, MySQL, PostgreSQL)
Running enterprise applications (SAP, Oracle)
Deploying web servers and application servers
Development and testing environments
Disaster recovery solutions

Managed Disks are a crucial component of building robust and scalable solutions on Azure. By leveraging their features, you can ensure your virtual machines have the reliable, high-performance storage they need to operate effectively.