1.Name node is in safe mode.

Solution: run in your Hadoop installation directory

bin/hadoop dfsadmin -safemode leave

User can operate the security mode through DFSADMIN -Safemode Value. The description of the parameter value is as follows:


ENTER -Entering Security Mode


Leave -Forced NameNode leave the security mode


GET -Back to the information of whether the security mode is turned on

Wait -wait until the security mode ends.

2.Caused by:org.datanucleus.exceptions.NucleusException: Attempt to invoke the”BONECP” plugin to create a ConnectionPool gave an error : Thespecified datastore driver (“com.mysql.jdbc.Driver”) was not found inthe CLASSPATH. Please check your CLASSPATH specification, and the name of thedriver.

This problem is caused by the lack of the driver packet corresponding to the database. Copy the driver package of the MySQL database to $ hive_home/lib/under

cp mysql-connector….jar $HIVE_HOME/lib/

3.Causedby:org.apache.hadoop.hive.ql.metadata.HiveException:org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:Hivemetastore database is not initialized. Please use schematool (e.g. ./schematool-initSchema -dbType …) to create the schema. If needed, don’t forget toinclude the option to auto-create the underlying database in your JDBCconnection string (e.g. ?createDatabaseIfNotExist=true for mysql))

This problem is because there is no initialized meta -database

schematool -initSchema –dbType mysql

4.Unable to instantiate org.apache.hadoop.hive.ql.metadata.SessionHiveMetaStoreClient

The reason why the problem is not started Metastore

hive --service metastore