Azure Disk Storage provides block-level storage for Azure Virtual Machines, offering high durability, scalability, and security. It includes five types of managed disks:

  1. Ultra Disks (Data Disk)
  2. Premium SSD v2 (Data Disk)
  3. Premium SSD (OS Disk & Data Disk)
  4. Standard SSD (OS Disk & Data Disk)
  5. Standard HDD (OS Disk & Data Disk)

Ultra Disks and Premium SSD v2 options are not available as OS disk.

These disks are automatically managed by Azure, meaning users only need to specify the disk type and size, while Azure handles provisioning and maintenance.

Azure Disks are a key component of storage in Azure, especially for Virtual Machines (VMs), and they can significantly impact overall cost depending on several factors.
In this article we will discuss mainly on selection of OS Disks and their impact on overall cost.

OS Disks mainly comes with following three options.
Premium SSD
Standard SSD
Standard HDD

We will discuss one by one below in short.

  1. Premium SSD

i. High performance, low latency disks.
ii. Best for production workloads like databases, high-transaction systems
iii. High cost due to IOPS and throughput capabilities.

Below is the snap of a basic windows virtual machine pricing with Premium SSD

PSSD

  1. Standard SSD

i. Lower-cost SSD option
ii. Good for web servers, dev/test, and general-purpose workloads
iii. Moderate cost, lower performance than Premium SSD

A snap of a basic windows virtual machine pricing with Standard SSD is given below

SSSD

  1. Standard HDD

i. Magnetic disk drives for low-cost, low-performance storage.
ii. Ideal for backups, infrequent access, archival.

Below is the price of a basic windows virtual machine with Standard HDD

SHDD

if you clearly go through the above images, you will see that how pricing is changing with the selection of different kind of disk drives.

For better understanding a comparison chart is given below:-
Here we have taken 128Gib as an example.
It can be clearly visible that price or cost is varying for different disk categories keeping the storage size constant.

comp

Conclusion:-
A. Choosing the over-provisioned disk type increases cost unnecessarily.
B. Match disk type and size to workload.
C. Regularly review and if required delete unattached disks.
D. Monthly audit to detect over-provisioned disk type and down-grade them as per requirement