Sometimes, in the face of initialize configuration and setup, it is easier to completely re-initialize an Accumulo installation than try to repair it. These steps are different than what might be found in the Apache ecosystem as the following steps are related to how Apache Ambari is used to install and configure Accumulo. Warning: the following steps (may) irreversibly remove all Accumulo related data. This includes table data, namespaces, table configuration, and Accumulo users. Do not perform these steps unless you are positive that you do not want to preserve any of the information. First, Accumulo must be stopped. This can be done via Ambari and verified using tools like `ps` on the nodes. Second, the Accumulo HDFS directory should be removed. This can be done by the HDFS superuser ("hdfs" by default) or the Accumulo user ("accumulo" by default). # sudo -u hdfs hdfs dfs -rm -R /apps/accumulo/data Next, Accumulo needs to re-initialized using the command line tools. This command must be executed from a node in your cluster where an Accumulo service is currently installed (the Accumulo Client is not sufficient). # sudo -u accumulo ACCUMULO_CONF_DIR=/etc/accumulo/conf/server accumulo init --instance-name hdp-accumulo-instance --clear-instance-name This command requires two pieces of information. The first we are providing as an argument to the command: the Accumulo instance name. By default, this name is "hdp-accumulo-instance" using Ambari; however, users may have provided their own value. As this name is how clients find and connect to Accumulo, it is important to use the correct name. The second piece of information is the Accumulo root user's password. You will be prompted for this information after running this command. This is only relevant when Kerberos authentication is not configured. When Kerberos is enabled, this command will prompt you for the full Kerberos principal of the user to grant Accumulo administrative (SYSTEM) permissions to. If this command successfully returns, you can restart Accumulo via Ambari. Visit the Accumulo Monitor page to verify that the system is online and/or use the proper Accumulo credentials to access the system via the Accumulo shell.
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