Relationship with Other Components

Relationship Between HDFS and HBase

HDFS is the subproject of Apache Hadoop. HBase uses the Hadoop Distributed File System (HDFS) as the file storage system. HBase is located in structured storage layer. The HDFS provides highly reliable support for lower-layer storage of HBase. All the data files of HBase can be stored in the HDFS, except some log files generated by HBase.

Relationship Between ZooKeeper and HBase

Figure 1 describes the relationship between ZooKeeper and HBase.

Figure 1 Relationship between ZooKeeper and HBase

1. HRegionServer registers itself to ZooKeeper in Ephemeral node. ZooKeeper stores the HBase information, including the HBase metadata and HMaster addresses.
2. HMaster detects the health status of each HRegionServer using ZooKeeper, and monitors them.
3. HBase can deploy multiple HMasters (like HDFS NameNode). When the active HMatser node is faulty, the standby HMaster node obtains the state information of the entire cluster using ZooKeeper, which means that HBase single point faults can be avoided using ZooKeeper.