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Introduction to VM Disks

Azure Virtual Machines (VMs) use disks to store the operating system, applications, and data. Understanding the different types of disks and how to manage them is crucial for optimizing performance, cost, and reliability of your Azure deployments. This documentation covers the essentials of Azure VM disks.

Azure Disk Types

Azure offers several types of managed disks, each with different performance characteristics and pricing. Choosing the right disk type depends on your workload's requirements:

  • Ultra Disk: High-performance, low-latency storage for I/O-intensive workloads.
  • Premium SSD: High-performance, low-latency SSD storage for most production workloads.
  • Standard SSD: Cost-effective SSD storage for development/test workloads and low-latency requirements.
  • Standard HDD: Cost-effective HDD storage for infrequently accessed data or archival.

You can find detailed specifications and performance metrics on the Azure Managed Disks pricing page.

Managed vs. Unmanaged Disks

Azure managed disks simplify disk management by handling the availability, durability, and scalability of storage. They are the recommended disk type for Azure VMs.

  • Managed Disks: Azure manages the storage account, data, and availability sets. You manage the disks themselves.
  • Unmanaged Disks: You are responsible for creating and managing the storage accounts where your virtual hard disks (VHDs) are stored. This offers more granular control but requires more operational overhead.

Common Disk Operations

You can perform various operations on Azure VM disks using the Azure portal, Azure CLI, or Azure PowerShell. Some common operations include:

  • Creating a disk: Provisioning a new disk of a specific type and size.
  • Attaching a disk: Connecting an existing disk to a VM.
  • Detaching a disk: Removing a disk from a VM.
  • Resizing a disk: Increasing the capacity of a disk.
  • Taking snapshots: Creating point-in-time copies of disks for backup or disaster recovery.
  • Cloning a disk: Creating a new disk from a snapshot.

For detailed command-line examples, refer to the Azure CLI VM Disk documentation.

Disk Performance Considerations

Disk performance is measured by IOPS (Input/Output Operations Per Second) and throughput (MBps). Each disk type has different limits. Factors that influence performance include:

  • Disk Type: Ultra, Premium SSD, Standard SSD, and Standard HDD offer varying performance levels.
  • Disk Size: Larger disks generally offer higher IOPS and throughput.
  • VM Size: The VM size also has limits on the total IOPS and throughput it can achieve.
  • Caching: Read-only or read-write caching can significantly improve performance for frequently accessed data.

Ensure your VM size and disk configuration align to meet your application's performance needs.

Pricing

Azure VM disk pricing is based on several factors:

  • Disk Type: Premium SSDs are more expensive than Standard HDDs.
  • Provisioned Size: The amount of storage you provision.
  • Data Transfer: Outbound data transfer from Azure regions incurs costs.
  • Snapshots and Backups: Storage for snapshots and backup data.

For detailed pricing information, please visit the Azure Managed Disks pricing page.