💽 Azure Disk Storage: Persistent Disk Storage for Virtual Machines

In cloud computing, persistent storage is critical for virtual machines (VMs) that require durable data storage. Azure Disk Storage provides block-level storage designed for Azure Virtual Machines, offering high-performance, low-latency storage options for a wide range of workloads.

Azure Disk Storage is ideal for databases, enterprise applications, development environments, and workloads requiring high IOPS. Unlike ephemeral storage that vanishes with the VM, Azure Disks persist independently and can be attached or detached as needed.

🔑 Key Features

• Persistent Storage → Data remains intact even if the VM is stopped or deleted.
• Multiple Disk Types → Standard HDD, Standard SSD, Premium SSD, Ultra Disk.
• High Performance → Designed for high IOPS and low latency applications.
• Managed and Unmanaged Disks → Managed disks are fully handled by Azure, unmanaged disks allow custom storage accounts.
• Snapshot Support → Create point-in-time copies of disks for backup.
• Encryption → Data encrypted at rest and optionally in transit.
• Scalability → Attach multiple disks to scale storage and performance.

⚙️ Types of Azure Disks

🖥️ Example Programs Using Azure Disk Storage

Azure Disk Storage can be provisioned via Azure Portal, CLI, PowerShell, and SDKs.

✅ Example 1: Create and Attach Disk Using Azure CLI

# Create a managed disk
az disk create \
  --resource-group MyResourceGroup \
  --name MyDisk \
  --size-gb 128 \
  --sku Premium_LRS

# Attach disk to VM
az vm disk attach \
  --resource-group MyResourceGroup \
  --vm-name MyVM \
  --name MyDisk

✅ Example 2: Create Disk Snapshot (PowerShell)

$resourceGroup = "MyResourceGroup"
$diskName = "MyDisk"
$snapshotName = "MyDiskSnapshot"

# Create snapshot
$snapshot = New-AzSnapshot -ResourceGroupName $resourceGroup `
                            -SnapshotName $snapshotName `
                            -SourceUri "/subscriptions/<sub_id>/resourceGroups/$resourceGroup/providers/Microsoft.Compute/disks/$diskName" `
                            -Location "EastUS" `
                            -CreateOption Copy
Write-Output "Snapshot created: $($snapshot.Name)"

✅ Example 3: Mount Disk on Linux VM

# List available disks
lsblk

# Create a filesystem
sudo mkfs -t ext4 /dev/sdc

# Mount disk
sudo mkdir /mnt/data
sudo mount /dev/sdc /mnt/data

# Make mount persistent
echo '/dev/sdc /mnt/data ext4 defaults,nofail 0 2' | sudo tee -a /etc/fstab

🧠 How to Remember Azure Disks for Interviews & Exams

1. Persistent = survives VM restart/deletion
2. Types = HDD, SSD, Premium, Ultra → Match workload requirements.
3. Snapshots = backup / point-in-time restore
4. Attachment = multiple disks per VM

Memory Tip: Think of Azure Disks as your VM’s cloud hard drive—durable, scalable, and high-performing.

🎯 Why Azure Disk Storage is Important

• Durable Storage → Ensures data integrity for critical applications.
• Scalable Performance → Attach multiple disks to handle higher workloads.
• Flexibility → Managed and unmanaged disks for different needs.
• Integration → Works seamlessly with VMs, Azure Kubernetes Service, and other services.
• Disaster Recovery → Snapshots enable easy backup and restore.
• Cost Optimization → Choose disk types according to performance needs.

🔥 Common Interview Questions

Q1: Difference between Managed and Unmanaged disks?

• Managed: Azure handles storage account management.
• Unmanaged: You manage the storage account.

Q2: What types of disks does Azure offer?

• Standard HDD, Standard SSD, Premium SSD, Ultra Disk.

Q3: How do you increase disk performance?

• Attach multiple disks or use Premium/Ultra disks.

Q4: Can disks be moved between VMs?

• Yes, managed disks can be detached and attached to other VMs.

🌍 Real-World Use Cases

1. Databases → SQL Server, Oracle, MySQL with high IOPS.
2. Enterprise Apps → SAP, Dynamics, and other mission-critical apps.
3. Development & Test Environments → Easily provisioned and persistent storage.
4. Hybrid Workloads → Extend on-premises storage to Azure Disks.
5. Disaster Recovery → Snapshots for backup and replication.

📖 Best Practices

• Choose the Right Disk Type → Align disk type with workload needs.
• Enable Disk Encryption → Azure-managed or customer-managed keys.
• Regular Snapshots → Protect against accidental data loss.
• Monitor Disk Performance → Use Azure Monitor for IOPS, latency, and throughput.
• Detach Unused Disks → Optimize cost and management.
• Use Disk Caching → Improve read/write performance for certain workloads.

🏆 Conclusion

Azure Disk Storage is an essential component for persistent VM storage in Azure. By understanding the types, performance characteristics, and management options, you can:

• Ensure high availability and durability for critical workloads.
• Scale performance using multiple disks or Premium/Ultra disks.
• Protect data using snapshots and backup strategies.
• Integrate seamlessly with VMs and cloud-native applications.

Interview Tip: Remember “Persistent, Scalable, Types, Snapshots, Attachments” to answer questions confidently.

Azure Disk Storage provides reliable, high-performance block storage that powers both traditional enterprise apps and modern cloud-native workloads, making it indispensable for cloud architects, developers, and IT professionals.