Azure Managed Disks

Understand and manage Azure disk storage for virtual machines.

Introduction to Azure Managed Disks

Azure Managed Disks simplify disk management for Azure Virtual Machines. Instead of managing storage accounts, you manage individual disks. Azure handles the infrastructure and availability of the disks.

Note: Unmanaged disks are legacy and not recommended for new deployments. Managed Disks offer improved availability, scalability, and management features.

Key Benefits of Managed Disks

  • High Availability: Managed Disks are stored as standard storage and are highly available within a storage scale unit.
  • Simplified Management: No need to manage storage accounts; disks are treated as resources.
  • Scalability: Easily scale disk performance and capacity.
  • VM Availability Sets: Managed Disks are automatically placed in a fault domain and update domain within the availability set for enhanced resilience.
  • Role-Based Access Control (RBAC): Granular control over who can access and manage disks.

Types of Managed Disks

Azure Managed Disks offer several types to meet different performance and cost requirements:

1. Ultra Disks

Ultra Disks are the highest-performance storage for Azure Virtual Machines. They offer configurable IOPS and throughput, making them ideal for I/O-intensive workloads like large databases, SAP HANA, and high-performance computing.

Features:

  • Up to 128,000 IOPS and 2,000 MB/s throughput per disk.
  • Bare-metal performance.
  • Provisioned performance is decoupled from capacity.

2. Premium SSD Disks

Premium SSD Disks provide low-latency, high-throughput solid-state drive (SSD) storage for I/O-intensive workloads. They are a cost-effective option for most production workloads, including development/test environments, small to medium databases, and web servers.

Features:

  • High performance with low latency.
  • Consistent and durable performance.
  • Various performance tiers (P1-P80) based on size.
az vm disk attach --vm-name MyVM --name MyPremiumDisk --resource-group MyResourceGroup --size-gb 128 --sku Premium_LRS

3. Standard SSD Disks

Standard SSD Disks offer a cost-effective solution for workloads that require consistent latency at an even lower price point than Premium SSDs. They are suitable for web servers, lightly used applications, and development/test environments.

Features:

  • Consistent latency compared to Standard HDD.
  • Lower cost than Premium SSDs.
  • Good for entry-level production workloads.

4. Standard HDD Disks

Standard HDD Disks provide the lowest cost per gigabyte for storing large amounts of data. They are best suited for workloads that are not sensitive to latency, such as backup, file servers, and less critical applications.

Features:

  • Lowest cost per GB.
  • Suitable for infrequently accessed data.
  • Higher latency compared to SSDs.
Best Practice: For most production workloads, start with Premium SSDs and scale up or down as needed. Consider Ultra Disks for mission-critical, high-performance applications.

Common Scenarios and Use Cases

  • Boot Disks: All Azure VMs come with an OS disk, which is a Managed Disk by default.
  • Data Disks: Attach additional Managed Disks to VMs to store application data, databases, and logs.
  • Shared Disks: Enable multiple VMs to attach and access the same disk concurrently for clustered applications (supported on Premium SSD and Ultra Disks).
  • Disk Encryption: Azure Disk Encryption provides full-disk encryption for OS and data disks using BitLocker and DM-Crypt.

Getting Started

You can create and manage Managed Disks using the Azure portal, Azure CLI, Azure PowerShell, or SDKs.

Example: Creating a Managed Disk using Azure CLI

# Create a resource group
az group create --name MyResourceGroup --location eastus

# Create a Standard SSD Managed Disk
az disk create --resource-group MyResourceGroup --name MyStandardSsdDisk --size-gb 512 --sku StandardSSD_LRS

# Create a Premium SSD Managed Disk
az disk create --resource-group MyResourceGroup --name MyPremiumSsdDisk --size-gb 256 --sku Premium_LRS

# Attach a disk to a Virtual Machine
az vm disk attach --vm-name MyVM --name MyPremiumSsdDisk --resource-group MyResourceGroup

Further Reading