Reviewing Disk Storage in Azure

Introduction

Azure virtual machines (VMs) use Azure disks as their attached disk storage. Azure disks are built-on top of page blobs which are the type of blobs optimized for random access. When you create Azure disks you can choose to manage the storage account yourself or to use managed disks where Azure manages the storage account for you. Managed disks are the preferred option. Within managed disks you can choose between:

• Ultra SSDs which provide the best throughput and I/O operations per second (IOPS) performance characteristics but at the highest prices. Consider Ultra SSDs for mission-critical I/O intense applications such as running databases.
• Premium SSDs are the next best performing and are well-suited to production workloads with all but the highest performance I/O requirements that may benefit from using Ultra SSDs.
• Standard SSDs are the least expensive SSD option and are suitable for production workloads with low I/O performance requirements such as web servers and lightly used applications.
• Standard HDDs use spinning disk technology and are therefore the least expensive option but also provide the lowest performance. Use them for backups and infrequently accessed applications.

Azure disks give you the freedom to attach and detach from different VMs. They will maintain their data but the data is only usable when a disk is attached to a VM. You will inspect a VM with two disks attached to it in this Lab Step.

Instructions

1. Click the upper-left accordion icon  to open the portal menu and click Virtual machines:

2. Click ca-lab-vm to view the overview of the VM created by the Cloud Academy Lab environment.

The VM is an ordinary Azure VM that is running the Windows Server operating system. You will focus on the VM's disks. 

3. In the left menu bar, click Disks under the Settings heading:

4. Observe the Azure disks that are attached to the VM:

Each VM has one OS disk which contains the operating system and is used to boot the VM. The OS disk is a Standard SSD in this case. In addition to the OS disk, VMs can have zero or more Data disks attached. This VM has one data disk that is a 4 GiB Standard HDD. All disks are encrypted at rest automatically and transparently to any users. This means if someone were to steal a physical disk from an Azure data center the physical disk would be encrypted and unusable. This is true for all data in Azure storage accounts. However, for Azure disks, you can also encrypt the virtual disk at the operating system level. This is referred to as Azure Disk Encryption (ADE). This protects against someone attempting to copy your Azure disk and attach it to an Azure VM because they would not be able to decrypt the data without the encryption key. Azure recommends enabling ADE for production workloads.

5. Click the name of the OS disk to view its overview.

You can see the disk is Attached to the lab VM (Managed by: ca-lab-vm) and the Operating system is Windows.

There are also visualizations showing how heavily utilized the disk is:

If you noticed a disk that reached the max throughput or IOPS you should consider upgrading to a higher performance disk type.

6. Observe the following screenshot that shows the Windows Explorer view of available disks from inside the Windows VM (Note: You don't need to access the VM in this step. The following screenshot is here just as a reference and to make a point): 

Azure automatically provides a Temporary Storage disk that will be lost forever once the VM is deleted. The temporary disk is useful for data that is temporary such as pagefile, which Azure configures to be placed in temporary storage when a new VM is provisioned. It is important to place data that is intended to persist into a persistent disk such as Azure disk. Azure disks can be attached and detached from VMs and persist their data. The data disk the VM has attached to it is not automatically formatted and does not appear in the list. Each operating system provides tools to format the data disks, but that is outside of the scope of this Lab.

Summary

In this Lab Step, you reviewed disk storage in Azure. Azure disks come in a variety of performance levels to allow you to meet your performance requirements at the lowest cost. Each VM has one OS disk and zero or more data disks.