Microsoft Azure Availability Set And Availability Zone 🧐

Pre-requisite Knowledge

Before we start with an understanding of what Microsoft Azure Availability Set is, we should know,

Basic knowledge of cloud computing and its services
Basic knowledge of Microsoft Azure
Basic knowledge of Virtual Machine

Background

In this article we will explore what is Microsoft Azure Availability Set. Before we look into it, let’s understand the following:

When we create the virtual machines in the Microsoft Azure cloud then it is important to think about the availability of the virtual machine’s hardware and software.
It is dependent on the percentage of time your application needs to available and accessible to keep business continuity. It can not be 100% in some cases.
Availability of virtual machine may impact because of fault domain and update domain.
Fault domain refers to unexpected hardware failure.
Update domain refers to predetermined software updates on Azure.
There can be hardware crash, power supply issues, hard disc crash, motherboard issues etc.
Also, there can be software issues such as updating the operating system which needs to be rebooted, operating system security updates etc.
In this situation we need to isolate thevirtual machines in the Azure data center, scale out the application with load balancer.
To make your application with high availability even with the failures then we should have availability set feature in place for Azure virtual machines.

Introduction of Microsoft Azure Availability Set

Azure Availability Set is a logical grouping capability for isolating Virtual Machines from each other when they are deployed in Azure data center.
When we put our Azure virtual machine in availability set feature then VMs are split into multiple faults and updated domains so that hardware failure or software updates should not impact on other virtual machines at the same time.
By default, Azure allocates the three fault domains and five update domains.
This limit can increase up to 20.
Microsoft offers 99.99% uptime for the servers in Availability set.
Microsoft recommends using the availability set feature to keep applications with high availability.
Availability Sets are critical for building reliable cloud solutions

Introduction of Microsoft Azure Availability Zone

Background

Cloud providers have data centers over all the world within different regions. Availability zone is an isolated location within a region from which cloud provider provides service to the cloud users. Every region can have one or multiple zones and they are isolated from each other. Each zone can have one or more multiple data centers with independent power, cooling, and networking. This is also needed for critical workloads with compliance, decrease latency and data authority requirements. Admin can move resources of applications within the zones in case of outage.

Microsoft Azure provides availability zones for high availability applications which protects data from data center failures.

Image Source – Microsoft Docs

The failure can be because of major two reasons,

Fault domain - refers to unexpected hardware failure.
Update domain - refers to predetermined software updates on Azure.

We can implement the zone redundant applications and data across the zones.
To make applications highly available and protect them from disaster receovery then replicate the components of applications with other zones.
We can use Azure Availability Set feature which is a logical grouping capability for isolating Virtual Machine from each other when they are deployed in the Azure data center.
Azure availability zone has two categories,

Zonal services – pin the resource to a specific zone (for example, virtual machines, managed disks, IP addresses)
Zone-redundant services – platform replicates automatically across zones (for example, zone-redundant storage, SQL Database).

There is no additional cost for availability zone VMs.
Microsoft claims 99.99% availability if we deploy two or more virtual machines across two or more availability zones within the Azure region.
Following regions are supported for availability zones in Azure cloud as of now,

Central US
East US
East US 2
West US 2
France Central
North Europe
UK South
West Europe
Japan East
Southeast Asia
Central US
East US
East US 2
West US 2
France Central
North Europe
UK South
West Europe
Japan East
Southeast Asia

Reference Links

https://docs.microsoft.com/en-us/azure/virtual-machines/windows/tutorial-availability-sets\
https://dev.to/kenakamu/azure-vs-gcp-part-10-virtual-machine---scaling-azure--4ci0
https://www.oreilly.com/library/view/architecting-microsoft-azure/9781788991735/d929b156-0f27-40bb-a112-7c775a8e35f7.xhtml

Conclusion

In this article we have learned the overview of Microsoft Azure Availability Set and Availability Zone. Keep Learning :)