In Huawei FusionInsight HD, the HBase component achieves high availability (HA) for its master node (HMaster) through an active/standby configuration managed by ZooKeeper. ZooKeeper, a distributed coordination service, is responsible for leader election. All HMaster instances in the cluster attempt to register an ephemeral node in ZooKeeper. The first instance to successfully create this node becomes the active HMaster. The other instances become standby masters and continuously monitor the ephemeral node. If the active HMaster fails, its session with ZooKeeper times out, the ephemeral node is deleted, and the standby masters initiate a new election process to select a new active master.

A. Random selection is not a fault-tolerant or reliable mechanism for electing a critical master process in a distributed system like HBase.

B. RegionServers are worker nodes responsible for data management and are controlled by the HMaster; they do not participate in the master election process.

D. While FusionInsight HBase uses a dual-master (or multi-master) model for high availability, an election ("ruling") process is absolutely required to determine which node is active and which is standby.

1. Huawei FusionInsight HD 6.5.1 Product Documentation, "Administrator Guide": Chapter: High Availability, Section: HMaster High Availability. This section details that the HMaster active/standby state is managed by ZooKeeper, which uses a leader election algorithm to ensure only one HMaster is active.

2. Huawei FusionInsight HD 6.5.1 Product Documentation, "Service Description - HBase": Section: HBase Architecture. The documentation illustrates the architecture where ZooKeeper is a core component for cluster coordination, including managing the state of the HMaster. It specifies ZooKeeper's role in service discovery and master election for HMaster.