private void exec(String hostname, ServiceType service, Operation op) throws IOException {
    execWithRetries(hostname, service, getCommandProvider(service).getCommand(service, op));
  }
Execute the given command on the host using SSH
@return pair of exit code and command output
@throws IOException if something goes wrong.
hbase-it/src/test/java/org/apache/hadoop/hbase/HBaseClusterManager.java