When your business-critical applications go down, every minute costs money. Here’s a step by step guide for IT managers and technical leaders deploying highly available services using Microsoft Azure. The challenge is making sure your services stay online when hardware fails, networks hiccup, or data centers experience problems.
This guide is exactly what you need for deploying highly available services using Microsoft Azure, based on real implementations we’ve built for enterprises across the EU. You’ll get practical steps, not theory, to keep your systems running when components fail.
What Does High Availability Mean in Cloud Architecture?
High availability means your services keep running even when parts of your infrastructure fail. Instead of trying to prevent every possible failure, you build systems that work around failures automatically.
When you are deploying highly available services using Microsoft Azure, you’re setting up:
- Redundant components so a single failure doesn’t take down your application
- Automatic failover that redirects traffic to healthy servers without anyone clicking buttons
- Geographic distribution that protects you from entire datacenter outages
- Continuous operation during maintenance and updates
For businesses running customer-facing applications, payment systems, or collaboration tools, high availability isn’t optional. One hour of downtime can mean lost revenue, damaged reputation, and regulatory problems.
Why Start Deploying Highly Available Services Using Microsoft Azure?
Azure gives you the building blocks when deploying highly available services using Microsoft Azure without buying duplicate hardware or managing complex failover scripts. The platform handles much of the heavy lifting that previously required dedicated infrastructure teams.
Here’s what matters when you start deploying highly available services using Microsoft Azure:
Multiple datacenters in Europe: Azure operates facilities in Amsterdam, Dublin, Frankfurt, Paris, and other European cities. You can spread your workloads across these locations to protect against regional problems while keeping data within EU boundaries for GDPR compliance.
Built-in redundancy options: Storage automatically replicates your data. Load balancers distribute traffic. Virtual machines can span availability zones. These aren’t add-ons—they’re core features you use to deploy highly available services in Azure.
Pay for what you use: Unlike traditional disaster recovery setups where you buy duplicate equipment that sits idle, Azure lets you run backup resources at lower cost and scale them up only when needed.
Integration with existing Microsoft investments: If you’re already using Active Directory, SQL Server, or other Microsoft technologies, your high availability architecture works with your current tools and skills.
Understanding Azure Availability Zones and Sets
Before you start, you need to understand how Azure organizes its infrastructure. This determines where your applications run and how they survive failures.
Availability Zones are physically separate datacenters within the same Azure region. Each zone has independent power, cooling, and networking. When you spread resources across availability zones, a fire, flood, or power outage at one datacenter won’t take down your application.
Think of zones this way: if you’re deploying in the West Europe region (Netherlands), your application runs simultaneously in three separate buildings. One building experiences problems? Your users never notice because the other two keep working.
Availability Sets group virtual machines within a single datacenter to protect against hardware failures and planned maintenance. Azure places VMs in different racks with separate power and network switches. When Microsoft needs to update server hardware, they work on one rack at a time, keeping your other VMs online.
Azure availability zones vs sets which should you use when you deploy highly available services in Azure?
- Use availability zones for critical applications that must survive datacenter-level failures. This is the right choice when downtime costs you money or violates SLAs.
- Use availability sets when you need protection from hardware failures but can tolerate brief regional outages. This costs less than zones but provides less protection.
- Use both for maximum resilience: deploy across zones, and within each zone use availability sets for additional redundancy.
Key Components
To start deploying highly available services using Microsoft Azure successfully, you need several components working together. Each piece handles a specific failure scenario.
Load Balancers
Azure Load Balancer distributes incoming traffic across multiple servers. When one server fails health checks, the load balancer stops sending it traffic. Your users connect to a single IP address, but their requests automatically route to whichever servers are healthy.
For public-facing applications, you’ll typically use Azure Application Gateway or Azure Front Door, which add features like SSL termination and web application firewall protection on top of basic load balancing.
Redundant Storage
Your application servers can fail over automatically, but if your data lives on a single disk, you still have a single point of failure. Azure Storage offers several redundancy levels:
- Locally redundant storage (LRS): Three copies within one datacenter
- Zone redundant storage (ZRS): Copies across three availability zones
- Geo-redundant storage (GRS): Copies to a secondary region hundreds of kilometers away
For databases, Azure SQL Database and Azure Database for PostgreSQL include built-in replication. You don’t manage backup servers yourself—you pick a service tier and Azure handles the redundancy.
Health Monitoring
You can’t fix failures you don’t detect. Azure Monitor watches your services and infrastructure, tracking metrics like CPU usage, memory consumption, and response times. When problems occur, Monitor triggers alerts to your team or automatically runs remediation scripts.
When you deploy highly available services in Azure, configure health probes that actively test your application endpoints. A server might be running but unable to process requests—health probes catch these scenarios before users complain.
Traffic Manager
Azure Traffic Manager routes users to the closest or best-performing instance of your application. If your primary region goes offline, Traffic Manager redirects everyone to your secondary region automatically. This DNS-based routing works across regions and even across cloud providers.
How to Start: Step-by-Step
Here’s how to actually start deploying highly available services using Microsoft Azure, from planning through production deployment.
Step 1: Planning Your Architecture
Start by documenting your availability requirements. Not every application needs five nines of uptime, and over-engineering costs money.
Define your Recovery Time Objective (RTO): How long can your application be down before it causes serious business impact? This determines whether you need active-active deployment across regions or can use a less expensive active-passive setup.
Define your Recovery Point Objective (RPO): How much data can you afford to lose? This determines your backup frequency and replication strategy.
Map your dependencies: List every service your application needs—databases, APIs, file storage, authentication. Each dependency needs its own high availability plan.
Choose your regions: Pick a primary Azure region close to your users. For critical applications, select a secondary region for failover. Keep GDPR in mind—if your data can’t leave the EU, choose European region pairs.
Step 2: Setting Up Redundancy
Now implement the actual redundant infrastructure to deploy highly available services in Azure.
Create a resource group for your high availability deployment. Keep all related resources together for easier management.
Deploy virtual machines across availability zones:
When creating VMs through Azure CLI or Portal, select your region (e.g., West Europe), choose “Availability zone” under availability options, select zones 1, 2, and 3, and deploy at least one VM in each zone.
Configure zone-redundant storage. When creating storage accounts, select ZRS redundancy to automatically replicate across availability zones.
Set up your database with high availability. For Azure SQL Database, choose the Business Critical or Premium tier, which includes built-in replicas across availability zones. For other databases, enable geo-replication to create readable secondaries.
Step 3: Configuring Load Balancers
Your redundant servers won’t help if traffic still goes to failed instances. Load balancers detect failures and redirect traffic automatically when you begin deploying highly available services using Microsoft Azure.
Create an Azure Load Balancer:
- Choose your tier (Basic for testing, Standard for production)
- Define your frontend IP address—this is what users connect to
- Create a backend pool containing your VMs across availability zones
- Configure health probes to test application health every 5-15 seconds
- Set up load balancing rules that distribute traffic to healthy backends
Configure health probes correctly. Test your actual application endpoint, not just the server. For a web application, probe an application health endpoint that checks database connectivity and critical dependencies, not just the homepage.
Add session persistence if needed. Some applications require users to stay connected to the same server. Configure session affinity (also called sticky sessions) when your application can’t handle distributed sessions.
Step 4: Monitoring and Failover
High availability isn’t “set and forget.” You need active monitoring and tested failover procedures.
Set up Azure Monitor alerts:
- CPU usage above 80% sustained
- Memory usage above 90%
- Health probe failures
- Increased error rates in application logs
- Slow response times
Create action groups that define who gets notified and how. For critical alerts, use SMS or phone calls, not just email.
Test your failover procedures regularly. Once per quarter, deliberately stop services in one availability zone and verify your application stays online. Test your monitoring by checking that alerts fire correctly.
Document your runbooks. When failures happen at 2 AM, your on-call engineer needs clear steps to assess the situation and take action. Document how to check system health, force failovers manually, and roll back changes.
Best Practices to Deploy Highly Available Services in Azure
Successfully deploying highly available services in Azure requires more than just checking boxes during initial setup. These practices separate systems that survive failures from systems that merely claim they will.
Design for failure: Assume every component will fail eventually. Your application code should handle database timeouts gracefully, retry failed operations with exponential backoff, and degrade gracefully when dependencies are unavailable. A highly available infrastructure can’t fix application code that crashes on every transient error.
Use managed services when possible: Azure SQL Database, Azure App Service, and Azure Kubernetes Service include high availability features you’d otherwise build yourself. Managed services reduce complexity and let you focus on your application, not infrastructure.
Implement circuit breakers: When a dependency fails, stop calling it repeatedly. Circuit breakers detect repeated failures and temporarily stop making requests, giving the failing service time to recover instead of overwhelming it.
Keep configurations in sync: Your primary and secondary regions must run identical configurations. Use infrastructure as code (Azure Resource Manager templates or Terraform) to ensure consistency. Configuration drift between regions causes failures during actual failover events.
Monitor your SLAs: Track your actual uptime and compare it to your goals. If you promise 99.9% availability, you have 43 minutes of acceptable downtime per month. Measure reality and adjust your architecture when you miss targets.
Plan for disaster recovery separately: High availability protects against component and datacenter failures. Disaster recovery protects against data corruption, malicious attacks, and catastrophic regional outages. You need both.
Size for failure scenarios: If you run three servers across availability zones for N+2 redundancy, each server must handle 50% of peak traffic, not 33%. When one zone fails, the remaining servers need capacity to absorb its load.
Common Mistakes When Deploying Highly Available Services Using Microsoft Azure
Even experienced teams make mistakes when they deploy highly available services in Azure. Here are the problems we see most often.
Single points of failure in dependencies: You configured redundant application servers but your database runs in a single zone. Or you use a third-party API that has no failover. Map every dependency and ensure each has its own high availability plan.
Untested failover procedures: Your architecture looks perfect on paper, but you’ve never actually triggered a failover. Then during a real outage, you discover your DNS takes 30 minutes to propagate or your application won’t connect to the secondary database. Test failovers quarterly under realistic conditions.
Ignoring network latency between zones: Availability zones are separate datacenters, typically several kilometers apart. This adds milliseconds of latency. For databases using synchronous replication, this latency appears in every write operation. Measure actual performance, don’t assume it’s identical to single-zone deployment.
Insufficient monitoring: You know your application is down because users are complaining, not because your monitoring alerted you. Implement comprehensive health checks that test actual functionality, and set up alerts that reach the right people reliably.
Cost surprises: Running duplicate infrastructure across zones costs money. Data transfer between zones costs money. If you don’t monitor spending, your high availability solution might be financially unsustainable. Set up Azure Cost Management alerts and review spending monthly.
Forgetting about stateful components: Load balancing works great for stateless web servers. Session state, uploaded files, and cached data require additional planning. Use Azure Redis Cache for sessions, Azure Storage for files, and design your application to handle any server processing any request.
Neglecting security: High availability means more infrastructure to secure. Each load balancer, each VM, each network path needs proper security configuration. Use Azure Security Center to identify configuration issues before attackers do.
Real-World Example: How We Helped a Financial Services Client Deploy Highly Available Services Using Microsoft Azure
A financial services company operating across six EU countries needed to deploy highly available services in Azure for their client portal. Their legacy system ran in a single datacenter, and even brief outages violated regulatory requirements and damaged client trust.
The challenge: The portal processes payment instructions, account inquiries, and document uploads for 50,000 business clients. Downtime during business hours was unacceptable, and EU data residency requirements meant all data must stay within European datacenters.
The solution: We architected a multi-zone deployment in Azure’s West Europe region:
- Application servers deployed across three availability zones using Virtual Machine Scale Sets
- Azure Application Gateway distributing traffic with health probes checking every 10 seconds
- Azure SQL Database Business Critical tier with zone-redundant configuration
- Zone-redundant storage for document uploads
- Azure Traffic Manager routing to North Europe region for disaster recovery
- Continuous monitoring through Azure Monitor with 24/7 alert response
The results: The platform has maintained 99.97% uptime over 18 months of production operation, including several infrastructure failures that occurred without client impact. Automated failover has activated twice during Azure maintenance windows, each time completing within seconds without any service interruption.
The architecture costs approximately 35% more than their previous single-zone setup, but the elimination of outage-related penalties and the improved client satisfaction have provided clear ROI.
Ready to Deploy Highly Available Services in Azure?
Learning when deploying highly available services using Microsoft Azure transforms your infrastructure from a potential risk into a reliable foundation for business growth. While the initial investment in redundancy and monitoring requires resources, the cost of downtime—in revenue, reputation, and competitive position—makes high availability essential for any serious business application.
Your next move depends on where you are today. If you’re planning a new Azure deployment, design for high availability from day one—retrofitting resilience costs more than building it initially. If you’re running applications in Azure already, assess your current architecture against these best practices and identify your biggest risks.
Need help when deploying highly available services using Microsoft Azure? Our cloud infrastructure team has designed and deployed highly available systems for enterprises across Europe. We can assess your requirements, design a solution tailored to your specific compliance and performance needs, and guide your team through implementation. Contact our specialists
Get your free Azure HA Deployment Checklist: Download our comprehensive PDF checklist covering every step to deploy highly available services in Azure, from initial planning through production validation. Download the checklist
About Ace Networks: We specialize in Information, Telephony, and Computing (ITC) development and IT consulting for enterprises across Europe. Our team holds advanced Microsoft certifications and has architected cloud solutions for clients in financial services, healthcare, manufacturing, and professional services. Based in the EU, we understand the technical and regulatory requirements of European businesses operating in Azure. Contact our team to discuss your cloud infrastructure needs.