Configure and Start Apache ZooKeeper
| ![[Tip]](../common/images/admon/tip.png) | Tip | 
|---|---|
| If you are running a highly available cluster, upgrade Apache ZooKeeper before you upgrade HDFS. This best practice lets the upgraded ZKFC work with your primary NameNode and your Standby NameNode. | 
RHEL/CentOS/Oracle Linux
- Replace your configuration after upgrading ZooKeeper. Replace the ZooKeeper template configuration in - /etc/zookeeper/conf.
- Start ZooKeeper. - On all the ZooKeeper server host machines, run the following command to start ZooKeeper and the ZKFC: - su - zookeeper -c "export ZOOCFGDIR=/usr/hdp/current/zookeeper-server/conf ; export ZOOCFG=zoo.cfg; source /usr/hdp/current/zookeeper-server/conf/zookeeper-env.sh ; /usr/hdp/current/zookeeper-server/bin/zkServer.sh start"- /usr/hdp/current/hadoop-client/sbin/hadoop-daemon.sh start zkfc
SLES
- Replace your configuration after upgrading. Replace the ZooKeeper template configuration in /etc/zookeeper/conf. 
- Start ZooKeeper. - On all the ZooKeeper server host machines, run the following command to start ZooKeeper and the ZKFC: - su - zookeeper -c "export ZOOCFGDIR=/usr/hdp/current/zookeeper-server/conf ; export ZOOCFG=zoo.cfg; source /usr/hdp/current/zookeeper-server/conf/zookeeper-env.sh ; /usr/hdp/current/zookeeper-server/bin/zkServer.sh start"- /usr/hdp/current/hadoop-client/sbin/hadoop-daemon.sh start zkfc
Ubuntu/Debian
- Replace your configuration after upgrading. Replace the ZooKeeper template configuration in /etc/zookeeper/conf. 
- Start ZooKeeper. - On all the ZooKeeper server host machines, run the following command to start ZooKeeper and the ZKFC: - su - zookeeper -c "export ZOOCFGDIR=/usr/hdp/current/zookeeper-server/conf ; export ZOOCFG=zoo.cfg; source /usr/hdp/current/zookeeper-server/conf/zookeeper-env.sh ; /usr/hdp/current/zookeeper-server/bin/zkServer.sh start"- /usr/hdp/current/hadoop-client/sbin/hadoop-daemon.sh start zkfc

