Written by Kate Kupriienko
Navigating the storm: AWS outage aftermath and your path to resilience
Remember October 20, 2025? For many, it was a day of frustration, lost productivity, and potentially significant financial impact. When Amazon Web Services (AWS), the backbone of countless online services, experienced widespread connectivity issues, the ripple effect was felt globally. From popular social media apps to banking services and airlines, businesses big and small found themselves grappling with unexpected downtime and revenue loss.
And now Azure? Just over a week later, Microsoft was also hit with an outage affecting its Azure and 365 services, proving that infrastructure failures are a systemic challenge, regardless of the cloud provider.
If your company was among those impacted, you're likely asking: "What can we do to prevent this from happening again? Or at least, how can we weather the next storm better?"
The real goal isn't to prevent every single fault, but to manage risk, build your infrastructure in a way that is resilient, and have a well-exercised incident response.
The good news is that while no system is 100% immune to failure, there's a lot you can do to build resilience into your infrastructure, minimizing the impact of future outages – whether they originate from your cloud provider or closer to home.
Let's dive into actionable strategies.
Outages are inevitable: how to build a more resilient cloud architecture?
First, an important clarification: aiming for 100% outage prevention in a complex, distributed system is an almost impossible goal. The sheer scale and intricate dependencies of modern cloud infrastructure mean that some level of component failure is a given.
The real goal isn't to prevent every single fault within your cloud provider's systems (something largely out of your direct control). Instead, it's about managing risk, building your infrastructure in a way that is resilient, and having a well-exercised incident response. It's about ensuring a single point of failure doesn't become your company's Achilles' heel.
Foundation: the tested disaster recovery playbook
Before you deploy complex multi-region architectures, you need an emergency battle plan: a Disaster Recovery Playbook. Technical redundancy is useless if your engineers are scrambling to figure out who does what and in what order when the alert sounds. While dedicated DevOps or SRE (Site Reliability Engineering) teams typically handle this planning, you shouldn't wait until you have a full professional team in place to start creating one.
A Playbook shifts the response from panicked improvisation to organized execution. It transforms a global incident into a manageable, documented procedure.
Your playbook Disaster recovery best practices typically include:
- Communication Flow: Who to notify (leadership, customers) and which secondary channel to use (e.g., dedicated Status Page or SMS).
- The "Runbook" Steps: Clear, practical, step-by-step instructions for recovery, including failover procedures and how to validate service status.
- Defined Roles: A clear Incident Commander, communications lead, and technical leads to ensure a calm, organized response.
🎯 Test it like a fire drill
A plan gathering dust is a risk. It's always a good idea to mock an outage and follow the plan with your team. Run a full-scale drill every now and then to test your assumptions, identify bottlenecks, and refresh knowledge. This practice is crucial for turning your Playbook into a muscle memory response.
Building resilience: simple and effective steps
What are the simple, effective steps for building resilience?
These strategies are often the easiest to implement and provide significant returns on your investment in resilience.
1. Embrace multiple availability zones (AZs):
Imagine an Availability Zone as a physically isolated data center within a larger cloud region. Each AZ has independent power, networking, and cooling. The most fundamental step for resilience is to distribute your applications and data across at least two AZs within your chosen AWS region.
Why it works: If an internal issue (like the network monitoring system problem cited in the AWS outage) affects one AZ, your services in the other AZ(s) can continue operating, keeping your application online.
The AZ Limitation: While Multi-AZ setups protect you from localized failures (like a power outage or cooling failure in one data center), they may not be enough for true continuity in cases like the October 2025 AWS incident. If the failure is systemic and impacts the whole region, dependance on a single region — even with multiple AZs — will leave your application offline. This is the core reason why you must consider the advanced step of Multi-Region deployment.
2. Automate monitoring and alerts:
You can't fix what you don't know is broken. Implement robust monitoring across your entire stack – from individual servers and databases to application performance metrics and user experience. Set up automated alerts that notify your on-call teams immediately when predefined thresholds are breached.
Why it works: Early detection is critical. Proactive monitoring helps you catch issues before they escalate into widespread outages, significantly reducing downtime.
3. Prioritize backups and test recovery:
Data is your most valuable asset. Automate frequent backups of all critical data and configurations. But a backup is only as good as its restorability. Regularly conduct disaster recovery (DR) drills to test your recovery procedures. This ensures your team knows exactly how to restore services and validate that your backups are viable. This helps you validate the work you’ve done in the “Foundational” stage.
Why it works: Minimizes data loss and ensures you can recover services quickly and confidently when an incident occurs.
4. Implement health checks and auto-scaling:
Use load balancers to distribute incoming traffic. When your application receives incoming requests from users, the load balancers sit at the gateway and decide which of your healthy servers (or application instances) should handle that request. Crucially, configure them to perform continuous "health checks" on your application instances. If an instance becomes unhealthy, the load balancer should automatically stop sending traffic to it. Combine this with auto-scaling to automatically adjust your resource capacity based on demand.
Why it works: Ensures traffic is only routed to healthy resources and allows your application to automatically adapt to sudden spikes in user load or unexpected resource failures.
Beyond the basics: What are the best practices for advanced infrastructure fortification?
For mission-critical applications where every second of downtime is costly, more sophisticated (and often more complex) strategies are essential.
1. Multi-region deployment (beyond Availability Zones):
While AZs protect against data center-level failures, what if an entire cloud region experiences a widespread outage (like the one that kicked off our discussion)? For your most critical services, consider deploying them across two or more distinct geographic AWS regions.
Why it works: A catastrophic event impacting one region won't affect your services running in another, allowing for seamless failover. This often involves "Active-Active" (both regions handle traffic) or "Active-Passive" (one region on standby) architectures.
2. Decoupling with microservices and bulkheads:
A common cause of widespread outages is a "cascading failure," where a problem in one component brings down seemingly unrelated parts of the system. Design your applications using a microservices architecture, where independent services communicate via well-defined APIs. Further, implement the Bulkhead Pattern – isolating resources so that a failure or overload in one service cannot exhaust the resources needed by other critical services.
Why it works: Prevents a single point of failure from triggering a chain reaction across your entire application. Think of a ship with watertight compartments – a breach in one doesn't sink the whole vessel.
3. Embrace chaos engineering:
Instead of waiting for an outage to expose weaknesses, proactively find them. Chaos Engineering involves intentionally injecting controlled failures into your systems (e.g., terminating random instances, simulating network latency, overloading a database) in a controlled environment.
If you're not breaking things on purpose, they'll break on their own at the worst possible time. Proactive testing reveals hidden weaknesses before a real-world outage exposes them.
Why it works: Helps you discover hidden vulnerabilities in your architecture, monitoring, and automated recovery processes before they cause a real-world outage. If you're not breaking things on purpose, they'll break on their own at the worst possible time. Proactive testing reveals hidden weaknesses before a real-world outage exposes them.
The path forward
The recent AWS outage was a stark reminder of our increasing reliance on complex cloud infrastructure. While it highlighted the fragility of interconnected systems, it also served as a powerful call to action for businesses.
By strategically implementing redundancy, robust monitoring, and proactive testing, you can significantly fortify your infrastructure against future disruptions. Start with the simpler steps, and as your business needs evolve, explore the more advanced strategies to build a truly resilient foundation that can withstand even the most unexpected outages. Your customers, and your bottom line, will thank you for it.