Region Pairing: The First Critical Consideration When Adopting Microsoft Azure

By Kevin Parker, Principal Solutions Architect for Microsoft Azure, Rackspace Technology

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You’ve decided that Microsoft® Azure® is your cloud of choice for managing workloads or building new applications. Now you need to get there. What is your first step?

Knowing your business motivation for moving to Azure is essential. But there is a consideration that is critical for gaining the agility, low-latency performance and security you want from your Azure cloud installation. As a practicing solutions architect for Azure at Rackspace Technology®, working with hundreds of customers, here’s what I wish every client knew before they deploy Azure.

When I talk to new customers about an Azure deployment, I begin by guiding them through one critical question — what region or regions will they be operating in? No matter what you plan to do with Azure, the first decision you need to make is where you are going to host your resources.


What is Region Pairing in Azure?

The reason I start here is that Azure has a feature that is unique among the big three cloud providers. It’s the concept of “region pairing.” Region pairing is the relationship between two Azure regions within the same geographic area to provide geographically redundant solutions. Azure’s paired regions are prewired with high bandwidth connectivity between them.

Azure operates in several geographies worldwide, and within a given geography or geopolitical boundary, each region is deployed along with another paired region. Some exceptions exist, such as Brazil, which is paired with South Central US, but these are edge cases. So, for example, in the US, Microsoft pairs Virginia (called East US 2) with Iowa (called Central US). So, if you are in East US 2 and a disaster recovery (DR) failover needs to occur, you’re still within a reasonable proximity to your secondary region and assured of a high level of service from a latency perspective. Contrast this with the original Virginia region, East US, which pairs with West US (California), and you are faced with a much higher latency should your environment need to failover.


Advantages of Region Pairing

Region pairing delivers three main advantages:

  • Geo-redundant storage services automatically replicate between region pairs
  • Microsoft prioritizes planned maintenances in a staggered manner across region pairs so that the same maintenance activity does not occur during the same window for both regions in a given pair
  • Region pairs have higher capacity network backbone connections between each region in the pair to accommodate the higher bandwidth requirements for geographic data replication, such as is common in a DR solution


Things to Consider

Choosing your region pair may seem obvious at first glance. You may assume that you just select your preferred primary region. However, there are a few upfront considerations that will help ensure you make the right choice from day one, including the following:

  • What are your growth plans? While you may operate in one region now, is there a possibility your organization will expand into new regions in the future? Do you currently have a growth plan in place that we need to include in the decision-making process?
  • Where are your customers and users located? Understanding your traffic is important because the closer your Azure environment is to your customers, the fewer latency issues you’ll have and the better their experience will be. Ideally, you want to deliver services based on proximity to users to ensure latency is minimized.
  • What is your budget for maintaining your Azure deployment? Each region operates under a different pricing structure based on the cost of, for example, real estate and utilities. So, if the price tag is critical, you’ll want to review regional cost variances before choosing your pairing.
  • Do you need access to specialized services for your Azure installation? While every region offers core services, such as virtual networks and storage, not every region provides specialized services, such as certain VM series or Data Lake Analytics. If you’re deploying in a region with a technical resource you need, but the paired region does not offer it, that may limit your ability to fail over to that region.

While you may not necessarily need to deploy across two paired regions when you initially deploy to Azure, you need to be aware that the region pairings exist because they should influence your region selection. This is critical to understand because the reality is that every organization is one major outage away from deciding they need a disaster recovery plan if they don’t have one already.


Region Pairing and Disaster Recovery

After determining which region pairs are ideal for your Azure deployment, the next major question is: What kind of resiliency do we need? Whether or not you want DR from day one, you should be aware of its impact on your Azure design choices regarding region pairing. For example, your paired region may someday need to operate your production workload(s) until the disaster event is resolved. This involves considering how Azure will be incorporated into your DR plan.

Questions to ask yourself are what is our tolerance for outages and how available do we need to be during a regional failure event? Many applications do not need 100% high availability. Others need 100% uptime.

One of my customers built their own DR plan in the East US Azure region without consulting an Azure architect regarding region pairs. The company planned to use its geo-redundant backups as part of a DR plan, using Central US as a failover region. But this did not work since East US is paired with West US. (East US 2 is paired with Central US). So we had to go in and delete everything they’d built in the Central US region and rebuild it all in the West US region. This has added roughly 20% to their DR costs, based on regional price differences for resources.

Another customer is not using geo-redundant storage for DR, and they’re okay with it. They understand how Azure region pairing works and understand the tradeoffs they have made.

Along with DR, another consideration is scheduled and unscheduled maintenance. Azure’s region pairing provides a benefit here as well — ensuring maximum uptime for companies and their customers. Thanks to its pairing architecture, Microsoft will stagger planned maintenance windows so that only one region from each pair is affected at a time, minimizing the risk of downtime associated with maintenance.


Solving Together™

While you should not focus exclusively on the technology at the expense of losing sight of solving your business challenges, there are certain technical aspects of every project that we can answer upfront. We want to ensure that your solution is designed to support optimal outcomes for your organization. Azure region pairings are one of these areas of consideration, but one that often gets overlooked.

Considering Azure region pairs early in the process can help ensure your organization gains all the advantages that can help you deliver better service, prevent latency risks, support agility and better manage costs.

Whether you’re looking to spur innovation and agility with Microsoft Azure cloud, lower costs or build operational efficiencies, we can help. We work with you to leverage this cloud solution to address your application and infrastructure challenges and help you create new revenue streams and increase efficiency.

The certified cloud experts at Rackspace Technology put cutting-edge capabilities to work for your business. We apply deep expertise in cloud strategy, cloud-native development, containers, application modernization, AI/ML Ops, IoT and workload management to help you accelerate innovation with Microsoft Azure.

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