Reliability & Failover

Always Online

Downtime is not an option. Every minute of outage costs money, reputation, and customer trust. We design architectures that tolerate the failure of single servers, entire availability zones, and even whole cloud regions.

Our philosophy: "Everything fails, all the time." We operate on the assumption that any component can fail at any moment, and we build systems that continue operating regardless.

Failover Strategies

DNS-Based Failover

The simplest form of failover operates at the DNS layer. When a health check detects an unhealthy endpoint, DNS records update to remove it from rotation:

• Health Check Design: We implement multi-layer health checks that verify not just that a server responds, but that the entire application stack is healthy.
• TTL Optimization: Balancing cache hit rates with failover speed. Lower TTLs mean faster failover but more DNS queries; we find the right balance for your requirements.
• Failover Cascade: Implementing tiered failover — first to other instances in the same region, then to other regions, then to degraded modes.
• DNS Provider Redundancy: Using multiple DNS providers to eliminate DNS as a single point of failure.

Limitation: DNS failover depends on clients respecting TTLs. Some clients cache aggressively, leading to continued traffic to failed endpoints. For critical workloads, we recommend combining DNS failover with other techniques.

Global Load Balancing

Global load balancers like AWS Global Accelerator or Google Cloud Load Balancing provide failover without relying on DNS TTL behavior:

• Anycast Entry Points: Users connect to the nearest edge location via Anycast, then traffic is routed over the provider's backbone to healthy backends.
• Instant Failover: Backend health changes are reflected in seconds, not dependent on client DNS cache behavior.
• Connection Draining: Graceful removal of unhealthy backends without dropping active connections.
• Geographic Routing: Directing users to the nearest healthy region for optimal latency.

Active-Active Deployment

For mission-critical workloads, Active-Active architectures provide the highest availability. Multiple regions serve live traffic simultaneously:

• No Cold Standby: All regions are warm and serving traffic, so there's no "failover" — just redistribution of load.
• Data Replication: Designing data replication strategies that maintain consistency while minimizing latency impact.
• Conflict Resolution: For write workloads, implementing conflict resolution strategies (last-write-wins, CRDTs, application-level resolution).
• Session Handling: Designing session management that works across regions — sticky sessions, distributed session stores, or stateless architectures.

Chaos Engineering

The best way to know your failover works is to test it — continuously, in production. We implement chaos engineering practices that validate resilience:

• Failure Injection: Controlled introduction of failures — server crashes, network partitions, dependency outages — to verify recovery.
• Game Days: Scheduled exercises where the team responds to simulated incidents, validating runbooks and on-call procedures.
• Continuous Chaos: Automated, ongoing chaos experiments in non-production environments (or carefully controlled production experiments).
• Chaos Tools: Implementation of chaos platforms like Chaos Monkey, Gremlin, Litmus, or AWS Fault Injection Simulator.

RTO and RPO Planning

Every disaster recovery strategy is defined by two metrics:

We help you define appropriate RTO/RPO targets for each workload based on business impact analysis, then design architectures that meet those targets cost-effectively.

Incident Response Automation

Human reaction time is measured in minutes; network incidents develop in seconds. We implement automated response that triggers before your on-call engineer even opens their laptop:

• Alert Correlation: Intelligent alerting that correlates multiple signals to reduce noise and identify root causes faster.
• Automated Remediation: Runbook automation that executes recovery procedures automatically for known failure modes.
• Traffic Management: Automated traffic shifting away from degraded components.
• Escalation Paths: Intelligent escalation that routes incidents to the right responders based on severity and component.
• Post-Incident: Automated incident timelines and context collection to accelerate post-mortems.

Reliability Deliverables

Every reliability engagement includes:

• Failure Mode Analysis: Documentation of potential failure modes and their expected impact
• Architecture Documentation: Diagrams showing redundancy, failover paths, and data flows
• Runbooks: Step-by-step procedures for handling common failure scenarios
• Chaos Test Results: Evidence that failover mechanisms work as designed
• Monitoring Dashboards: Visibility into system health and failover status
• RTO/RPO Validation: Measured recovery times and data loss for tested scenarios