How to Restore a Missing Data Disk from a Snapshot in Azure
Exhibit
Recovery notes: - VM: vm-finance-01 - Data disk: disk-finance-logs was deleted accidentally - Snapshot: snap-finance-logs-2024-11-15 exists in the same subscription - Goal: restore the disk with minimal impact to the operating system disk
Based on the exhibit, what should the administrator do first to restore the missing data disk?
Quick Answer
The correct first step is to create a managed disk from the snapshot, then attach it to the VM. This is necessary because the snapshot is a point-in-time copy of the missing data disk, not the OS disk, so you cannot simply boot from it or attach it directly; Azure requires you to first provision a managed disk resource from that snapshot, which then becomes a usable, persistent disk object. On the AZ-104 exam, this scenario tests your understanding of Azure disk recovery workflows and the distinction between OS and data disk snapshots—a common trap is attempting to attach the snapshot itself or redeploying the VM, which wastes time and risks data loss. Remember the recovery chain: snapshot → managed disk → attach to VM. For a memory tip, think “Snap to Disk, then Attach”—you always snap a snapshot into a disk before you can plug it into a live machine.
⚠ Common exam trap
Many candidates confuse a data disk snapshot with an OS disk snapshot and attempt to replace the VM's OS disk, or assume that Azure automatically recreates missing disks when resizing the VM.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a managed disk from the snapshot, then attach it to the VM.
The snapshot represents the missing data disk, not the OS disk. To restore it, you must first create a managed disk from the snapshot (using Azure CLI, PowerShell, or portal), then attach that disk to the VM. This preserves the existing VM configuration and applications without redeployment.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Create a managed disk from the snapshot, then attach it to the VM.
Why this is correct
A snapshot is a point-in-time copy of a disk, and the normal recovery path is to create a new managed disk from that snapshot. After the disk is created, it can be attached to the VM or a recovery VM. This keeps the OS disk untouched and minimizes impact while restoring the missing data volume.
- ✗
Recreate the VM from the marketplace image and restore applications manually.
Why it's wrong here
Rebuilding the whole VM is far more disruptive than restoring only the deleted data disk.
When this WOULD be correct
This option would be correct if the question asked: 'An administrator needs to replace a corrupted OS disk on a VM that was created from a marketplace image. The VM has no custom data on the OS disk. What should the administrator do first?'
- ✗
Convert the snapshot directly into an operating system disk and replace the VM.
Why it's wrong here
The snapshot represents the deleted data disk, not the OS disk, so replacing the VM is unnecessary.
When this WOULD be correct
This option would be correct if the question stated that the VM's OS disk was corrupted or missing, and the snapshot was taken from the original OS disk. In that scenario, creating a managed disk from the snapshot and attaching it as the OS disk would restore the VM's operating system.
- ✗
Increase the VM size so that Azure automatically recreates the missing disk.
Why it's wrong here
Changing VM size does not restore deleted managed disks or recover snapshot data.
When this WOULD be correct
In a scenario where a VM is experiencing performance issues due to insufficient IOPS or throughput, and the question asks for the first step to resolve the issue, increasing the VM size (to a larger SKU) would be correct to provide better disk performance.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-104 exam frequently reuses these exact scenarios with slightly different constraints.
✓Create a managed disk from the snapshot, then attach it to the VM.Correct answer▾
Why this is correct
A snapshot is a point-in-time copy of a disk, and the normal recovery path is to create a new managed disk from that snapshot. After the disk is created, it can be attached to the VM or a recovery VM. This keeps the OS disk untouched and minimizes impact while restoring the missing data volume.
✗Recreate the VM from the marketplace image and restore applications manually.Wrong answer — click to see why▾
Why this is wrong here
The question is about restoring a missing data disk, not the OS disk or the entire VM. Recreating the VM from the marketplace image would lose all OS-level customizations and applications, and does not restore the data disk.
★ When this WOULD be the correct answer
This option would be correct if the question asked: 'An administrator needs to replace a corrupted OS disk on a VM that was created from a marketplace image. The VM has no custom data on the OS disk. What should the administrator do first?'
Why candidates choose this
Candidates may think that recreating the VM is a straightforward way to fix disk issues, especially if they are unaware that snapshots can be used to create managed disks and attach them to existing VMs.
✗Convert the snapshot directly into an operating system disk and replace the VM.Wrong answer — click to see why▾
Why this is wrong here
Converting a snapshot directly into an OS disk and replacing the VM would overwrite the operating system, not restore a missing data disk. The snapshot is of a data disk, not an OS disk, so this action would corrupt the VM's OS.
★ When this WOULD be the correct answer
This option would be correct if the question stated that the VM's OS disk was corrupted or missing, and the snapshot was taken from the original OS disk. In that scenario, creating a managed disk from the snapshot and attaching it as the OS disk would restore the VM's operating system.
Why candidates choose this
Candidates may confuse a data disk snapshot with an OS disk snapshot, or assume that any snapshot can be used to replace the entire VM, overlooking the distinction between OS and data disks.
✗Increase the VM size so that Azure automatically recreates the missing disk.Wrong answer — click to see why▾
Why this is wrong here
Increasing VM size does not automatically recreate missing data disks; Azure only adjusts compute and storage capacity, not individual disk attachments.
★ When this WOULD be the correct answer
In a scenario where a VM is experiencing performance issues due to insufficient IOPS or throughput, and the question asks for the first step to resolve the issue, increasing the VM size (to a larger SKU) would be correct to provide better disk performance.
Why candidates choose this
Candidates may mistakenly believe that Azure automatically manages disk redundancy or recreation when resizing, confusing VM resizing with disk repair actions.
Analysis generated from the official AZ-104blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Managed Identities for Azure Resources
Key term
Azure CLI
Azure CLI is a command-line tool that lets you manage Azure resources by typing commands instead of clicking through a web portal.
Key term
Managed disk
A managed disk is a cloud-based virtual hard drive that Azure automatically creates, manages, and scales for your virtual machines so you don't have to worry about storage infrastructure.
About these practice questions
This AZ-104 question is part of Courseiva's 1,049-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on AZ-104
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A data disk on VM-Data01 was corrupted after a bad patch, and you already have a snapshot taken last night. The OS disk should remain unchanged. Which two actions should you take to restore only the data disk? Select two.
hard- ✓ A.Create a managed disk from the snapshot.
- ✓ B.Attach the restored managed disk to VM-Data01.
- C.Redeploy the VM and expect the data disk to revert automatically.
- D.Generalize the VM and redeploy it from the snapshot.
- E.Replace the snapshot with the current data disk to roll back the VM.
Why A: A snapshot is a point-in-time copy of a disk that can be used to create a new managed disk. Since you have a snapshot of the corrupted data disk from last night, creating a managed disk from that snapshot restores the data to its state at the time of the snapshot, leaving the OS disk untouched.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-104 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the AZ-104 exam.