Cloudera Docs

Perform hostname changes

You need to bring the Kudu clusters down to update the hostnames. Therefore, identify at least a one-hour maintenance window for this task.

  1. Rewrite each master’s Raft configuration with the following command, executed on each master host: 
    $ sudo -u kudu kudu local_replica cmeta rewrite_raft_config --fs_wal_dir=<master_wal_dir> [--fs_data_dirs=<master_data_dir>] 00000000000000000000000000000000 <all_masters>
    For example:
    $ sudo -u kudu kudu local_replica cmeta rewrite_raft_config --fs_wal_dir=/data/kudu/master/wal --fs_data_dirs=/data/kudu/master/data 00000000000000000000000000000000 4aab798a69e94fab8d77069edff28ce0:new-master-name-1:7051 f5624e05f40649b79a757629a69d061e:new-master-name-2:7051 988d8ac6530f426cbe180be5ba52033d:new-master-name-3:7051
  2. Update the master address:
    • In an environment not managed by Cloudera Manager, change the gflag file of the masters so the master_addresses parameter reflects the new hostnames.
    • In an environment managed by Cloudera Manager, specify the new hostname in the Master Address (server.address) field on each Kudu role.
  3. Change the gflag file of the tablet servers to update the tserver_master_addrs parameter with the new hostnames. In an environment managed by Cloudera Manager, this step is not needeed.
  4. Start the masters.
  5. To verify that all masters are working properly, perform the following sanity checks:
    1. In each master’s Web UI, click Masters on the Status Pages. All of the masters should be listed there with one master in the LEADER role field and the others in the FOLLOWER role field. The contents of Masters on all master should be the same.
    2. Run the below command to verify all masters are up and listening. The UUIDs are the same and belong to the same master as before the hostname change: 
      $ sudo -u kudu kudu master list new-master-name-1:7051,new-master-name-2:7051,new-master-name-3:7051
  6. Start all of the tablet servers.
  7. Run a Kudu system check (ksck) on the cluster using the kudu command line tool. After startup, some tablets may be unavailable as it takes some time to initialize all of them.
  8. If you have Kudu tables that are accessed from Impala, update the HMS database manually in the underlying database that provides the storage for HMS.
    1. The following is an example SQL statement you run in the HMS database: 
      UPDATE TABLE_PARAMSSET PARAM_VALUE =
'new-master-name-1:7051,new-master-name-2:7051,new-master-name-3:7051'
WHERE PARAM_KEY = 'kudu.master_addresses'
AND PARAM_VALUE = 'master-1:7051,master-2:7051,master-3:7051';
    2. In impala-shell, run: 
      INVALIDATE METADATA;
    3. Verify updating the metadata worked by running a simple SELECT query on a Kudu-backed Impala table.