AZ-104 Deploy and Manage Azure Compute Practice Question
A company has an Azure VM running a production workload. The VM's OS disk is currently a Standard HDD. The administrator needs to improve the disk performance for the OS disk without recreating the VM. What should the administrator do?
⚠ Common exam trap
The trap here is thinking that resizing the VM or adding disks will improve OS disk performance, when the disk type itself must be changed.
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
✓
Change the OS disk to a Premium SSD by using the Azure portal or Azure CLI.
Managed disks support changing the performance tier without recreating the VM. Upgrading the OS disk from Standard HDD to Premium SSD increases IOPS and throughput, directly improving performance. The other options either do not affect the OS disk performance or are not supported.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Add a new data disk and move the OS to it.
Why it's wrong here
You cannot move the operating system to a data disk after the VM is created. The OS disk is a special disk that contains the boot volume, and it must remain as the OS disk. Adding a data disk does not improve the performance of the existing OS disk.
- ✗
Resize the VM to a larger size that includes a temporary disk.
Why it's wrong here
Resizing the VM may change the temporary disk size and CPU/memory, but it does not change the performance tier of the OS disk. The temporary disk is not persistent and cannot be used for the OS. To improve OS disk performance, the disk type itself must be changed.
- ✗
Enable read-only caching on the OS disk.
Why it's wrong here
Read-only caching can improve read performance for data disks, but it is not supported for OS disks. The OS disk uses read/write caching by default. Changing caching settings on the OS disk is not possible beyond the default, so this does not address the need to improve OS disk performance.
- ✓
Change the OS disk to a Premium SSD by using the Azure portal or Azure CLI.
Why this is correct
Azure allows you to change the performance tier of a managed disk, including the OS disk, without recreating the VM. You can upgrade from Standard HDD to Premium SSD to achieve lower latency and higher throughput. This is the correct approach to improve disk performance while keeping the VM intact.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
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.