Answer:- Nagios is a very commonly used support tool for gaining qualitative data regarding cluster status. It polls current metrics on a regular basis and compares them with given thresholds.

Answer:- The syntax of describe command is – hbase> describe tablename

Answer:- The exists command is used to check that the specified table is exists or not.

Answer:- MasterServer is used to assign a region to the region server and also handle the load balancing.

Answer:- HBase shell is a java API by which we communicate with HBase.

Answer:- The zookeeper is used to maintain the configuration information and communication between region servers and clients. It also provides distributed synchronization.

Answer:- Catalog tables are used to maintain the metadata information.

Answer:- The cell is the smallest unit of HBase table which stores the data in the form of a tuple.

Answer:- Compaction is a process which is used to merge the Hfiles into the one file and after the merging file is created and then old file is deleted. There are different types of tombstone markers which make cells invisible and these tombstone markers are deleted during compaction. Become Master of Apache HBase by going through this online HBase Course.

Answer:- HColumnDescriptor stores the information about a column family like compression settings , Number of versions etc.

Answer:- It is a MasterServer which is responsible for monitoring all regionserver instances in a cluster.

Answer:- There are two types of Compaction i.e. Minor Compaction and Major Compaction.

Answer:- It is a RegionServer implementation which is responsible for managing and serving regions.

Answer:- PageFilter accepts the pagesize as the parameter.