Core infrastructure: scalability, resilience and disaster recovery

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This article describes the infrastructure used for Black Pear Core.



Static content for Black Pear apps is hosted as a Microsoft Azure Web App 

Black Pear services that process data are hosted on Amazon Web Services (AWS) using a Virtual Private Cloud (VPC) in the EU (London) region [eu-west-2].


Connection to NHS networks is provided by Redcentric, an NHS approved N3 aggregator, using an approved Logical Connection Architecture. Redcentric use AWS Direct Connect to provide a physical connection between NHS networks and the VPC.

Third parties

Some services used for additional Core modules are dependent on APIs provided by Black Pear partners: NHS England, EMIS Health, TPP and Vision Health.



Web App static content is available from multiple data centres across Europe to ensure continuity of service in the event of failure in one data centre.

Services processing data are hosted in multiple AWS availability zones in the EU (London) region. For each service, a minimum of N+1 instances are deployed in conjunction with a load balancer in active-active configuration to ensure continuity of service in the event of failure of an instance. Instances are deployed across multiple availability zones (think of an availability zone as a data centre) to ensure continuity of service in the event of a failure in one availability zone. It is not possible to provide continuity in the event of failure of the entire region as this would require the services to process data outside the UK.

Automated health checks are used to detect and replace failed instances; autoscaling is used to detect services reaching capacity limits and to add extra instances to provide additional capacity.

Two network connections are deployed at different physical locations. These operate in an active-passive configuration to ensure continuity of service in the event of failure at one location.

Business Continuity and Disaster Recovery testing is conducted at least annually.


All hosted services are routinely deployed using CloudFormation templates to provide fast and repeatable deployments.


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