HI @mabilgen , The main problem that you have on this cluster is lack of RAM on the host which is limited to 128GB. The Namenodes while startup will consume the allocated heap of 98GB that leaves 30GB of memory for any other processes running on this host.   When other processes also utilise this remaining 30GB of memory, you are seeing huge JVM pauses as the garbage collector is trying to de-reference the objects to free up the memory but this takes too much time that the Namenode gives up on the Journalnode Quorum and fails over.   As a Thumb rule, you should allocate 1GB of heap for 1 million blocks. So if there are more than 98million blocks on this cluster, then the current NN heap is not sufficient.   1) Try to lower the Total block count on the cluster by deleting any unwanted files or old snapshots. 2) If feasible, add more Physical RAM to the host   Any amount of tunings won't be helpful in this situation as the jvm pauses are too big to be managed by tunings. As such, you would need to either perform cleanup of HDFS or Add more RAM to NN hosts or Move Namenode to another Node which has higher RAM. ... View more

Hi @ditto  You can use API to start the services. To Stop and Start a CDH service, you could try to make use of the CM APIs such as the below, Start the service - POST /clusters/{clusterName}/services/{serviceName}/commands/start Stop the service - POST /clusters/{clusterName}/services/{serviceName}/commands/stop   https://cloudera.github.io/cm_api/apidocs/v6/path__clusters_-clusterName-_commands_stop.html https://cloudera.github.io/cm_api/apidocs/v6/path__clusters_-clusterName-_commands_start.html https://cloudera.github.io/cm_api/apidocs/v6/index.html ... View more