To set up disaster recovery for your Azure Data Factory (ADF) instances located in France and Germany, ensuring that both can connect and function as alternatives in case of failure, you can implement the following strategy:

Follow the below steps to setup disaster recovery for azure data factory:

Step1: Install SHIR on your On-Premises Machine and start by downloading the SHIR installation package from the Azure portal. Now Install the SHIR on your on-premises machine, to meet all system requirements.

Step2: Register SHIR with the First ADF Instance to Access the Azure portal and navigate to the first ADF instance. Now Go to Manage > Integration > Runtimes > +New and select Self-Hosted and proceed with the registration process. Copy the provided authentication key and enter it into the SHIR configuration on your on-premises machine.

Step3: Register SHIR with the Second ADF Instance and Repeat the registration process for the second ADF instance. Navigate to the second ADF instance in the Azure portal.

Go to Manage > Integration > Runtimes > +New. Click on Self-Hosted and follow the process to register the SHIR. once doe this process Configure the SHIR on your on-premises machine and create a new authentication key for the second instance.

Step4: Avoid Linked Integration Runtimes and Do not use linked IRs if you need both ADF instances to function independently. Linked IRs may fail if one IR is unavailable, which is not suitable for your disaster recovery needs.

Step5: To ensure continuous operation, implement high availability for the SHIR. This will provide redundancy and ensure that ADF instance can access the SHIR independently, even if one instance goes down.

Step6: Regularly check for updates to the SHIR installation. Keeping the SHIR up to date will help you benefit from the latest features, performance improvements, and security patches.

Note: Please refer these articles, article1, article2, article3 for more information on setting up and configuring a Self-Hosted Integration Runtime (SHIR) in Azure Data Factory.