For a production-ready and highly available FusionInsight cluster, specific node counts are recommended. Management nodes are deployed in a two-node active/standby configuration to prevent a single point of failure (SPOF). A minimum of three control nodes is required to establish a ZooKeeper quorum, which is essential for the high availability (HA) of other critical services like HDFS NameNode and YARN ResourceManager. Finally, a minimum of three data nodes is necessary to accommodate the default HDFS data block replication factor of three, ensuring data reliability and fault tolerance across different physical nodes.

A. A single management node is a SPOF, and two control/data nodes are insufficient for standard ZooKeeper quorum and HDFS replication.

B. A single management node is not recommended for a highly available cluster as it creates a single point of failure.

C. A single data node cannot satisfy the default HDFS replication factor of three, leading to under-replicated data blocks.

1. Huawei FusionInsight HD 6.5.1 Product Documentation, "Cluster Planning > Node Planning". Document ID: 3150-01. This document explicitly states: "Management nodes are deployed in active/standby mode. Therefore, two management nodes need to be planned... To ensure high availability, it is recommended that you deploy at least three control nodes... To ensure data reliability, HDFS stores three replicas of data by default. Therefore, at least three data nodes need to be deployed."

2. Huawei FusionInsight HD Administrator Guide, "System Architecture > High Availability (HA) Design", Section 2.3. This section details the necessity of two management nodes for the OMS active/standby mechanism and the requirement of an odd number of nodes (minimum three) for the ZooKeeper quorum, which underpins the cluster's overall HA strategy.

3. Huawei FusionInsight HD Technical White Paper, "HDFS Architecture and Principles", Section 3.2 "Data Replication". This paper explains that the default replication factor (dfs.replication) is set to 3 to ensure data durability against node failures, making a minimum of three DataNodes a prerequisite for a standard deployment.