The statement is false. Huawei FusionInsight HD is designed for enterprise environments where operational flexibility is crucial. After a successful installation, administrators can and must be able to modify configurations to tune performance, scale the cluster, and adapt to changing workloads. The FusionInsight Manager, the platform's management console, provides comprehensive functionalities to modify service parameters, add or delete role instances, and manage the overall cluster configuration dynamically.

The "True" option is incorrect because it suggests a static, unchangeable cluster state post-installation. This is fundamentally impractical for any production-level big data system. The inability to modify configurations would prevent administrators from performing essential tasks such as performance tuning, resource allocation adjustments, scaling out nodes, or applying security updates, rendering the cluster unmanageable in the long term.

1. Huawei FusionInsight HD 6.5.1 Administrator Guide: In the section titled "Cluster Management," there are detailed procedures for managing cluster resources post-installation. Specifically, Chapter 5, "Managing Services," outlines the steps for modifying service configuration parameters. For example, Section 5.4, "Modifying Service Configuration Parameters," explicitly details how an administrator can change settings for services like HDFS, YARN, and others through the FusionInsight Manager interface.

2. Huawei FusionInsight HD 6.5.1 Administrator Guide: The guide also describes how to scale the cluster by adding or removing components. Chapter 4, "Managing Hosts," and Chapter 5, "Managing Services," provide instructions for adding new hosts to the cluster and then deploying new role instances (e.g., a new DataNode or NodeManager) onto those hosts. This directly contradicts the claim that roles and instances cannot be modified.

3. Huawei FusionInsight HD Product Documentation (for various versions): Across all official documentation for FusionInsight HD, the Operation and Maintenance (O&M) and Administrator Guides consistently feature sections on "Configuration Management," "Cluster Expansion," and "Service Management." These sections are dedicated to post-installation modifications, which are considered standard administrative tasks. The existence of these extensive guides confirms that configuration is meant to be modified.