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Migrate IBM z/OS OLTP workloads to Azure

Azure Front Door
Azure Traffic Manager
Azure Kubernetes Service (AKS)
Azure Spring Apps
Azure Cache for Redis

Online transaction processing (OLTP) systems are the face of your business because they interact directly with customers. By migrating to a dynamically adaptable infrastructure, your business can create and launch products quickly so that customers can use your products sooner.

Architecture

The following diagram shows an architecture of an OLTP system that runs on a z/OS mainframe before migration to Azure:

Diagram of an OLTP architecture on z/OS.

Workflow

The following workflow corresponds to the preceding diagram:

  1. Users connect to the mainframe over Transmission Control Protocol (TCP) or Internet Protocol (IP) by using standard mainframe protocols like TN3270 and HTTPS.

  2. The transaction managers interact with the users and invoke the application to satisfy user requests.

  3. In the front end of the application layer, users interact with the Customer Information Control System (CICS) or Information Management System (IMS) screens or with webpages.

  4. The transaction managers use the business logic written in common business-oriented language (COBOL) or Programming Language One (PL/I) to implement the transactions.

  5. Application code uses the storage capabilities of the data layer, such as DB2, IMS DB, or VSAM.

  6. In addition to transaction processing, other services provide authentication, security, management, monitoring, and reporting. These services interact with all other services in the system.

The following diagram shows how to migrate this architecture to Azure.

Diagram that shows an architecture to migrate a z/OS OLTP workload to Azure.

Download a Visio file of this architecture.

  1. Mainframe users are familiar with 3270 terminals and on-premises connectivity. In the migrated system, they interact with Azure applications via the public internet or via a private connection that's implemented via Azure ExpressRoute. Microsoft Entra ID provides authentication.

  2. Input requests go to a global load balancer service, like Azure Front Door or Azure Traffic Manager. The load balancer can serve a geographically spread user base. It routes the requests according to rules defined for the supported workloads. These load balancers can coordinate with Azure Application Gateway or Azure Load Balancer to load balance the application layer. The Azure Content Delivery Network service caches static content in edge servers for quick response. A web application firewall (WAF) helps secure the service.

  3. The front end of the application layer uses Azure services like Azure App Service to implement application screens and to interact with users. The screens are migrated versions of the mainframe screens.

  4. COBOL and PL/I code in the back end of the application layer implement the business logic. The code can use services and features like Azure Functions, WebJobs, and Azure Spring Apps microservices. Applications can run in an Azure Kubernetes Service (AKS) container.

  5. An in-memory data store accelerates high-throughput OLTP applications. Examples include In-Memory OLTP, which is a feature of Azure SQL Database and Azure SQL Managed Instance, and Azure Cache for Redis.

  6. The data layer can include:

    • Files, tables, and blobs implemented by using Azure Storage.
    • Relational databases from the Azure SQL family.
    • Azure implementations of the PostgreSQL and MySQL open-source databases.
    • Azure Cosmos DB, which is a NoSQL database.

    These stores hold data migrated from the mainframe for the application layer to use.

  7. Azure-native services like Application Insights and Azure Monitor proactively monitor the health of the system. You can integrate Azure Monitor Logs by using an Azure dashboard.

Components

This architecture consists of several Azure cloud services. It's divided into four categories of resources: networking and identity, application, storage, and monitoring. The following sections describe the services for each resource and their roles.

Networking and identity

When you design application architecture, it's crucial to prioritize networking and identity components to help ensure security, performance, and manageability during interactions over the public internet or private connections. The following components in the architecture are essential to address this requirement effectively.

  • ExpressRoute carries private connections between on-premises infrastructures and Azure datacenters.

  • Microsoft Entra ID is an identity and access management service that can synchronize with an on-premises directory.

  • Azure Front Door provides global HTTP load balancing with instant failover. Its caching option can quicken the delivery of static content.

  • Traffic Manager directs incoming Domain Name System requests based on your choice of traffic-routing methods.

  • An Azure WAF helps protect web apps from malicious attacks and common web vulnerabilities, such as SQL injection and cross-site scripting.

  • Content Delivery Network caches static content in edge servers to enable rapid responses and uses network optimizations to improve response for dynamic content. Content Delivery Network is especially useful when the user base is global.

  • Application Gateway is an application delivery controller service. It operates at layer 7, the application layer, and has various load-balancing capabilities.

  • Load Balancer is a layer 4 (TCP or User Datagram Protocol) load balancer. In this architecture, it provides load balancing options for Azure Spring Apps and AKS.

Application

Azure provides managed services that support more secure, scalable, and efficient deployment of applications. The application-tier services that the preceding architecture uses can help you optimize your application architecture.

  • Azure API Management supports the publishing, routing, securing, logging, and analytics of APIs. You can control how the data is presented and extended and which apps can access it. You can restrict access to your apps or allow third parties.

  • App Service is a fully managed service for building, deploying, and scaling web apps. You can build apps by using .NET, .NET Core, Node.js, Java, Python, or PHP. The apps can run in containers or on Windows or Linux. In a mainframe migration, the front-end screens or web interface can be coded as HTTP-based REST APIs. They can be segregated according to the mainframe application and can be stateless to orchestrate a microservices-based system.

  • WebJobs is a feature of App Service that runs a program or script in the same instance as a web app, API app, or mobile app. A web job can be a good choice for implementing sharable and reusable program logic. For more information, see Run background tasks with WebJobs in App Service.

  • AKS is a fully managed Kubernetes service for deploying and managing containerized applications. AKS simplifies deployment of a managed AKS cluster in Azure by offloading the operational overhead to Azure.

  • Azure Spring Apps is a fully managed Spring service, jointly built and operated by Microsoft and VMware. You can use Azure Spring Apps to easily deploy, manage, and run Spring microservices and write Spring applications by using Java or .NET.

  • Azure Service Bus is a reliable cloud messaging service for simple hybrid integration. Service Bus and Storage queues can connect the front end with the business logic in the migrated system.

  • Azure Functions provides an environment for running small pieces of code, called functions, without having to establish an application infrastructure. You can use it to process bulk data, integrate systems, work with Internet of Things, and build simple APIs and microservices. Use microservices to create servers that connect to Azure services and are always up to date.

  • Azure Cache for Redis is a fully managed in-memory caching service for sharing data and state among compute resources. It includes open-source Redis and Redis Enterprise, a commercial product from Redis Labs, as a managed service. You can improve the performance of high-throughput OLTP applications by designing them to scale and to use an in-memory data store such as Azure Cache for Redis.

Storage and database

This architecture addresses scalable and more secure cloud storage as well as managed databases for flexible and intelligent data management.

Monitoring

The following monitoring tools provide comprehensive data analysis and valuable insights into application performance.

  • Azure Monitor collects, analyzes, and acts on personal data from your Azure and on-premises environments.

    Azure Monitor alerts are a feature of Monitor. For more information, see Create, view, and manage metric alerts using Azure Monitor.

  • Log Analytics is a tool in the Azure portal that you use to query Azure Monitor Logs by using a powerful query language. You can interact with the results of your queries or use them with other Azure Monitor features, such as log query alerts or workbooks. For more information, see Overview of Log Analytics in Azure Monitor.

  • Application Insights is a feature of Azure Monitor that provides code-level monitoring of application usage, availability, and performance. It monitors the application, detects anomalies such as mediocre performance and failures, and sends personal data to the Azure portal. You can also use Application Insights for logging, distributed tracing, and custom application metrics.

Scenario details

Because of evolving business needs and data, applications must scale and produce results without creating infrastructure problems. This example workload shows how you can migrate a z/OS mainframe OLTP application to a more secure, scalable, and highly available system in the cloud by using Azure platform as a service (PaaS) services. This migration helps businesses in finance, health, insurance, and retail minimize application delivery timelines. It also helps reduce the costs of running the applications.

Potential use cases

This architecture is ideal for OLTP workloads that have the following characteristics:

  • They serve an international user base.

  • Their usage varies greatly over time, so they benefit from flexible scaling and usage-based pricing.

Considerations

These considerations implement the pillars of the Azure Well-Architected Framework, which is a set of guiding tenets that you can use to improve the quality of a workload. For more information, see Well-Architected Framework.

Reliability

Reliability helps ensure that your application can meet the commitments that you make to your customers. For more information, see Design review checklist for Reliability.

  • You can deploy this OLTP architecture in multiple regions. It can also have a geo-replicated data layer.

  • The Azure database services support zone redundancy and can fail over to a secondary node if an outage occurs or to allow for maintenance activities.

Security

Security provides assurances against deliberate attacks and the misuse of your valuable data and systems. For more information, see Design review checklist for Security.

  • ExpressRoute creates a private connection to Azure from an on-premises environment. You can also use site-to-site VPN.

  • Microsoft Entra ID can authenticate resources and control access by using Azure role-based access control.

  • Database services in Azure support various security options like data encryption at rest.

  • For general guidance about how to design more secure solutions, see Security quick links.

Cost Optimization

Cost Optimization focuses on ways to reduce unnecessary expenses and improve operational efficiencies. For more information, see Design review checklist for Cost Optimization.

Use the Azure pricing calculator to estimate costs for your implementation.

Operational Excellence

Operational Excellence covers the operations processes that deploy an application and keep it running in production. For more information, see Design review checklist for Operational Excellence.

This scenario uses Azure Monitor and Application Insights to monitor the health of the Azure resources. You can set alerts for proactive management.

Performance Efficiency

Performance Efficiency refers to your workload's ability to scale to meet user demands efficiently. For more information, see Design review checklist for Performance Efficiency.

  • This architecture uses Azure PaaS services like App Service, which has autoscaling capabilities.

  • For more information, see Autoscaling.

Contributors

Microsoft maintains this article. The following contributors wrote this article.

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Next steps

See the following related architectures and related technical information.