Azure Virtual Machines Storage Concepts
Understanding how Azure Virtual Machines (VMs) interact with storage is crucial for designing efficient, reliable, and cost-effective solutions. Azure VMs leverage a variety of storage options, each with its own characteristics and use cases.
Managed Disks
Managed Disks are the recommended approach for managing storage for Azure VMs. They are blob storage objects that represent virtual hard disks (VHDs). Azure manages the storage account for you, simplifying operations and offering higher availability.
- Types of Managed Disks:
- Ultra Disk: For the most demanding I/O intensive workloads, offering sub-millisecond latency and high throughput.
- Premium SSD: High-performance, low-latency SSDs suitable for production workloads that require consistent performance.
- Standard SSD: Cost-effective SSDs for workloads that require consistent latency at an infrequent I/O level, such as dev/test environments, small to medium web servers.
- Standard HDD: Lowest cost option, suitable for backups, non-critical workloads, or data that is infrequently accessed.
- Benefits: High availability (99.999% SLA for availability sets), built-in redundancy, simplified management, and performance tiers.
Conceptual diagram of Azure Managed Disks.
Unmanaged Disks
With unmanaged disks, you are responsible for managing the storage accounts where your VHDs are stored. While still supported, Managed Disks are generally preferred for new deployments due to their inherent advantages.
- VHDs are stored as page blobs in Azure storage accounts.
- Requires manual management of storage account performance, redundancy, and scaling.
Temporary Storage
Most Azure VM sizes come with a local temporary disk. This storage is temporary and is hosted on a drive physically attached to the host computer running the VM. It's ideal for temporary data such as swap files or page files. Data on the temporary disk is lost if the VM is stopped (deallocated) or moved to a different host.
Blob Storage for VMs
While Managed Disks abstract away the underlying blob storage, it's useful to understand the types of blobs that represent VHDs:
- Page Blobs: Used for both unmanaged disks and Managed Disks. Optimized for random read/write operations.
Data Deduplication and Compression
Azure Storage offers capabilities for data deduplication and compression, which can help reduce storage costs and improve network efficiency. These features are often configured at the storage level, either within the guest OS or at the storage service layer.
Choosing the Right Storage
The selection of storage for your Azure VMs depends on factors such as:
- Performance requirements: IOPS, throughput, latency.
- Cost constraints: Budget for storage.
- Availability and durability needs: SLA requirements.
- Data access patterns: Frequency of access, sequential vs. random access.