hi all     I want to ask this important question   lets say we have the following:   HDP cluster with  :   3 masters machine ( active/standby name-node ) , ( active/standby resource manager ) 3 datanode machines     - each data-node machine have 4 disks for HDFS ( not include the OS ) 3 kafka machines    - each kafka machine have one disk of 10T ( not include the OS )   now we want to install from scratch all cluster include HDP and ambari   but save the data on datanode machines and kafka topics data machine by the following:   we umount the disks on datanode machines and kafka machines       example   on datanode machine ( note - /etc/stab is already configured )   umount /grid/data1 umount /grid/data2 . . .     so the second scratch installation we install all the cluster ( by blueprint ) , but without data-node HDFS disks , and kafka  topic disk ( scratch installation means fresh new linux OS )   after installation we mount all data-node machines disks and kafka disks machines ( where we are store all topics )  example   on datanode machine ( note - /etc/stab is already configured )   mount /grid/data1 mount /grid/data2 . . .     in order to complete the picture , need to restart  HDFS and YARN and kafka   so - is this scenario could to work ?   ... View more