Virtual Machines Storage

This document provides comprehensive information on managing storage for your Azure Virtual Machines (VMs), covering managed disks, unmanaged disks, and performance considerations.

Managed Disks

Managed Disks are the recommended storage option for Azure VMs. They simplify storage management by handling availability, redundancy, and scalability of the underlying storage infrastructure. Azure manages the storage account for you.

  • Types of Managed Disks:
    • Premium SSD: High-performance, low-latency disk storage for I/O-intensive workloads.
    • Standard SSD: Cost-effective SSD for workloads requiring consistent performance at lower IOPS.
    • Standard HDD: Lowest cost, highest density disk for workloads that are not sensitive to performance.
  • Benefits:
    • Simplified management
    • High availability and durability
    • Scalability
    • Disaster recovery features

Unmanaged Disks

Unmanaged Disks require you to manage the storage accounts where your virtual hard disks (VHDs) are stored. While still supported, Managed Disks are generally preferred for new deployments.

  • You are responsible for creating and managing storage accounts.
  • VHDs are stored as page blobs in Azure Storage.
  • Can be useful for migrating existing applications that rely on direct storage account management.

Choosing the Right Disk Type

The choice of disk type depends heavily on your application's workload and performance requirements:

  • For demanding applications like SQL databases, SAP HANA, or high-performance computing, choose Premium SSD.
  • For web servers, development/test environments, or applications with moderate I/O needs, Standard SSD offers a good balance of performance and cost.
  • For batch processing, infrequent access data, or less critical workloads where cost is the primary concern, Standard HDD is a suitable option.

Disk Performance

Understanding disk performance metrics is crucial for optimizing your VM's throughput and latency:

  • IOPS (Input/Output Operations Per Second): Measures the number of read/write operations a disk can perform per second.
  • Throughput (MB/s): Measures the amount of data that can be transferred per second.

Each VM size has a maximum limit for IOPS and throughput that it can utilize. Ensure your VM size can support the performance requirements of the attached disks.

Tip: For production workloads, always use Managed Disks. Consider Azure Disk Encryption for sensitive data.

Attaching and Detaching Disks

You can attach data disks to a VM during creation or to an existing VM. Similarly, data disks can be detached when no longer needed.

For detailed steps on managing disks, refer to the Azure portal documentation or use the Azure CLI and Azure PowerShell.

Key Concepts

  • OS Disk: Contains the operating system. Its size and performance are determined by the VM size and configuration.
  • Data Disks: Used to store application data and are independent of the OS disk.
  • Ephemeral OS Disks: Stored on the VM's local storage, offering lower latency and faster VM deployment. Suitable for stateless workloads.

For more advanced topics like disk bursting, storage replication, and cost optimization, please consult the full Azure VM storage guide.