AWS Public Sector Blog

Achieving “five nines” in the cloud for justice and public safety

Every hour of every day, our nation’s first responders and 9-1-1 personnel rely on a patchwork of telecommunications and public safety applications to protect their residents and save lives. Whether it’s a 9-1-1 answering point, a computer aided dispatch (CAD) system, a records management (RMS) system, or a mobile communications network, emergency response systems must be available and operational at all times. Downtime is not an option.

The accepted availability standard for emergency response systems is 99.999% or “five nines” – or about five minutes and 15 seconds of downtime per year (see table below). To achieve five nines, all components of the system must work seamlessly together. Software applications, compute resources, networking functionality, and physical data center services must be highly available to achieve five nines.

Achieving five nines in the cloud

Cloud computing can help lower an organization’s barrier to entry to achieve high availability. Amazon Web Services (AWS) offers emergency response systems architectures by building highly resilient systems in the cloud that employ computing models from instances to serverless and more. This is done by deploying in multiple Availability Zones (AZs) and replicating data between Regions to meet demanding recovery time and recovery point objectives, as well as service availability of 99.999% or higher.

“Increasingly, public safety agencies are starting to rely on cloud-enabled solutions to deliver mission-critical services to communities,” said Yosh Kakkad, CIO, San Diego Sheriff’s Office. “Innovative cloud-enabled solutions help ensure the underlying platform is reliable and highly available, translating to 99.999% availability and uptime.”

Each AWS Region has multiple AZs, which helps with fault tolerance and low latency. AZs are connected to each other with fast, private fiber-optic networking, enabling easy architecture of applications that automatically failover between AZs without interruption. AWS services are deployed in multiple AWS Regions and utilize a multi-zone architecture within each Region to deliver resilience and continuous availability. With this, customers avoid having a critical service dependency on a single data center. AWS conducts maintenance activities without making any critical service temporarily unavailable to any customer.

When calculating the availability of a system, it’s important to understand the difference between independent, decoupled services and services that have hard dependencies upon each other. AWS uses independent, redundant Availability Zones to maximize the uptime of each service component. Without such an approach, the presence of multiple service components cumulatively decreases the uptime of the overall system.

The theoretical availability is computed as 100% minus the product of the component failure rates (100% minus availability). For example, if a system uses two independent components, each with an availability of 99.9%, the resulting system availability is > 99.99%:Using this logic for the outlined architecture: Figure 1 (three-tier application) is a reference architecture of a system built in the AWS Cloud that can achieve five nines using services such as Amazon Elastic Compute Cloud (Amazon EC2), Elastic Load Balancing (ELB), and Amazon Aurora deployed in a Virtual Private Cloud (VPC). It also uses multiple availability zones in both AWS Regions with Amazon Route 53 for health-based routing of client traffic.

Figure 1: Three-Tier AWS Optimized Application

Figure 1: Three-Tier AWS Optimized Application

Figure 2 shows how these solutions could be designed to be serverless by using services such as AWS Lambda, Amazon DynamoDB, and Amazon API Gateway to power an application.

Figure 2: AWS Serverless Application

Figure 2: AWS Serverless Application

To connect with an AWS expert to learn more about how you can use AWS to make five nines computing an affordable reality, visit AWS for government. Learn how justice and public safety organizations are using AWS.