Introduction

Deploying Exchange Server 2019 in a multi-site environment requires careful planning to ensure high availability, load balancing, and disaster recovery across different geographic locations. This guide walks you through the necessary steps to configure Exchange Server 2019 in a multi-site setup, covering key considerations such as network design, Database Availability Groups (DAGs), and client access.

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1. Planning Your Multi-Site Deployment

Before starting the deployment, it’s crucial to plan the architecture and understand the key components involved.

1.1. Understanding Multi-Site Deployments

• A multi-site deployment involves installing Exchange Server 2019 across multiple physical locations (sites). This setup is typically used to ensure business continuity and provide local access to services for users in different regions.

1.2. Network Design Considerations

• Ensure reliable and fast network connections between sites. A multi-site deployment relies heavily on the network for communication between servers in different locations.
• Use dedicated connections for site-to-site communication to minimize latency and avoid disruptions in service.

1.3. Active Directory Site Topology

• Each physical location should be represented as a separate Active Directory site. Configure Active Directory sites and services to reflect your physical network topology.

1.4. IP Addressing and DNS Configuration

• Implement site-specific IP subnets and ensure that DNS is correctly configured to route traffic appropriately between sites.

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2. Preparing for Multi-Site Deployment

2.1. Setting Up Active Directory

• Ensure that Active Directory is healthy and that replication is functioning properly across all sites. Extend the schema for Exchange Server 2019 if this hasn’t been done already.

2.2. Installing Exchange Server Prerequisites

• Install necessary Windows features and roles on all servers in each site. Ensure that all servers meet the system requirements for Exchange Server 2019.

2.3. Configuring Firewalls and Load Balancers

• Configure firewalls to allow necessary traffic between sites. Implement load balancers to distribute client connections across multiple servers within and across sites.

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3. Deploying Exchange Server 2019 in Multiple Sites

3.1. Installing Exchange Server in the First Site

• Begin by installing Exchange Server 2019 in the first site. This site will act as the primary site, hosting the initial Active Directory configuration and Exchange services.
• Follow the standard installation process, ensuring that you configure URLs, certificates, and mail flow settings specific to this site.

3.2. Installing Exchange Server in Additional Sites

• Repeat the installation process in the secondary sites. Ensure that each site is configured with its own set of Exchange servers.
• During installation, ensure that all servers are part of the same Exchange organization and that they can communicate with the primary site’s Active Directory.

3.3. Configuring Database Availability Groups (DAGs)

• Create a Database Availability Group (DAG) that spans multiple sites to provide high availability and site resilience.
• Add mailbox servers from each site to the DAG and configure the necessary DAG networks. Ensure that the replication between sites is optimized for performance and reliability.

3.4. Configuring Witness Server for DAG

• Deploy a witness server in a third site or in Azure for the DAG. This helps in avoiding split-brain scenarios and ensures that quorum is maintained during site failures.

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4. Configuring Client Access in a Multi-Site Environment

4.1. Configuring Client Access Namespaces

• Set up unique internal and external namespaces for each site. This allows clients to connect to the closest site, reducing latency and improving user experience.

4.2. Load Balancing Client Connections

• Use load balancers to distribute client connections within each site. Implement global load balancing to direct clients to the nearest site geographically.

4.3. Configuring Outlook Anywhere and Autodiscover

• Ensure that Outlook Anywhere and Autodiscover are configured correctly for a multi-site deployment. Autodiscover should direct clients to their local site by default, with failover to another site if needed.

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5. Implementing High Availability and Disaster Recovery

5.1. Cross-Site DAG Configuration

• Ensure that mailbox databases are replicated across sites in the DAG for high availability. Set up automatic failover between sites to minimize downtime in the event of a site failure.

5.2. Site Resilience Considerations

• Implement site resilience by ensuring that all critical services, including Client Access and Transport, are available in each site. Regularly test failover procedures to ensure they work as expected.

5.3. Backup and Recovery Planning

• Configure backups for all Exchange servers and databases across sites. Implement a robust disaster recovery plan that includes off-site backups and recovery testing.

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6. Testing and Validation

6.1. Testing DAG Failover

• Test DAG failover between sites to ensure that mailboxes can be quickly and seamlessly moved from one site to another without data loss.

6.2. Client Access Testing

• Test client access from various geographic locations to ensure that users are being routed to the correct site and that all services are available.

6.3. Monitoring and Maintenance

• Implement monitoring solutions to keep track of the health and performance of your multi-site deployment. Regularly review logs and performance metrics to preemptively address issues.

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7. Best Practices for Multi-Site Deployments

• Geographic Distribution: Distribute your Exchange servers and DAG members across multiple sites to enhance resilience and performance.
• Network Redundancy: Use redundant network links between sites to ensure continuous availability even in case of network failures.
• Regular Testing: Regularly test failover and disaster recovery procedures to ensure your environment can handle unexpected failures.
• Documentation: Maintain detailed documentation of your multi-site Exchange deployment, including network configurations, DAG setups, and failover procedures.

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Conclusion

Deploying Exchange Server 2019 in a multi-site environment requires careful planning and execution to ensure high availability, load balancing, and disaster recovery. By following this guide, you can establish a robust and resilient Exchange environment that meets the needs of your geographically dispersed organization.

For further assistance or advanced configurations, consult additional Knowledge Base articles or contact our support team.