OnCommand Unified Manager (now Active IQ Unified Manager) is the correct tool for this task. It is designed to monitor and manage multiple ONTAP clusters from a single, centralized console. A core feature of Unified Manager is its ability to provide comprehensive monitoring and reporting on data protection relationships, including SnapMirror replication. It can discover all replication relationships across the managed clusters and present them in a consolidated view, allowing an administrator to generate reports on their status, lag time, and overall health for the entire infrastructure.

A. OnCommand System Manager: This tool is used for managing a single ONTAP cluster. It cannot provide a consolidated, comprehensive report across multiple, separate clusters as required by the scenario.

B. Storage Replication Adapter: SRA is a software plug-in that integrates NetApp storage with third-party disaster recovery orchestration software, such as VMware Site Recovery Manager (SRM), not a reporting tool.

D. OnCommand Workflow Automation: This is an automation tool used to create and execute custom storage management workflows. While a custom report could potentially be built, it is not its primary function for out-of-the-box comprehensive reporting.

1. NetApp Active IQ Unified Manager Documentation, "Data protection overview": "Unified Manager enables you to monitor the SnapMirror and SnapVault relationships in your clusters to ensure that your data is protected and that the secondary storage systems are ready to take over in case the primary storage systems have issues." This confirms its role in monitoring replication across clusters.

Source: NetApp Product Documentation, Active IQ Unified Manager 9.10, "Data protection overview".

2. NetApp Active IQ Unified Manager Documentation, "Monitoring data protection relationship health": "The Protection/Relationships page provides an overview of the health of all your data protection relationships. You can view details about a specific relationship to identify and resolve issues." This highlights its capability to provide a comprehensive view of all relationships.

Source: NetApp Product Documentation, Active IQ Unified Manager 9.10, "Monitoring data protection relationship health".

3. NetApp ONTAP System Manager Documentation: "You can use System Manager to manage a cluster and its storage objects..." The documentation consistently refers to managing "a cluster" (singular), confirming its scope is limited to a single entity.

Source: NetApp Product Documentation, ONTAP 9.12.1, "ONTAP System Manager overview".