What is the relationship between HBase and Apache Hadoop?

In HBase, ZooKeeper plays a crucial role as a coordination service. Specifically, ZooKeeper is primarily used in HBase for the following purposes:

1. Coordinating distributed services: HBase is a distributed database system where its various nodes require coordination and communication. ZooKeeper acts as a coordinator, assisting different HBase nodes in distributed coordination and management.
2. Metadata Storage: HBase utilizes ZooKeeper to store and manage critical metadata information, such as table structures and the distribution of regions. This metadata is crucial for the proper functioning of HBase, and managing it through ZooKeeper ensures consistency and reliability.
3. Leader election: In the HBase cluster, ZooKeeper is also responsible for assisting in the leader election process to ensure high availability of all nodes in the cluster. With the help of ZooKeeper, HBase can ensure smooth operation in case of node failures or network partitions.

In general, ZooKeeper plays a role in coordinating and leader election in HBase, helping HBase clusters achieve distributed coordination, metadata management, and high availability assurance.