Key points

• Persistent block storage resources attached to Azure VMs.
• OS disks boot VMs; data disks hold independent application data.
• Disk type, capacity, performance, caching, redundancy, and attachment affect workload behavior.

Best-known use cases

• Attach persistent data capacity to a VM.
• Snapshot a disk before a risky change.

What candidates often confuse it with

• OS disk vs data disk: boot volume vs separate application volume.
• Managed disk resize vs guest expansion: Azure allocation change vs filesystem or partition change inside the VM.

Key takeaway

Choose managed disk properties for workload performance and lifecycle, then complete any required guest operating-system changes.

Related services

• Azure Virtual Machines
• Encryption at host

Relevant exam tasks

• D3.2.S1 — Create a virtual machine
• D3.2.S2 — Configure encryption at host for Azure virtual machines
• D3.2.S3 — Move a virtual machine to another resource group, subscription, or region
• D3.2.S4 — Manage virtual machine sizes
• D3.2.S5 — Manage virtual machine disks

Learn more

• Azure managed disks documentation