ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded) • --usage • --version Command-Line Format --usage Command-Line Format --version Display help text and exit; same as --help. Display version information and exit. ndbmtd  is a multithreaded version of  ndbd , the process that is used to handle all the data in tables using the  NDBCLUSTER  storage engine.  ndbmtd  is intended for use on host computers having multiple CPU cores. Except where otherwise noted,  ndbmtd  functions in the same way as  ndbd ; therefore, in this section, we concentrate on the ways in which  ndbmtd  differs from  ndbd , and you should consult Section 23.4.1, “ndbd — The NDB Cluster Data Node Daemon” , for additional information about running NDB Cluster data nodes that apply to both the single-threaded and multithreaded versions of the data node process. 23.4.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded) Command-line options and configuration parameters used with  ndbd  also apply to  ndbmtd . For more information about these options and parameters, see Section 23.4.1, “ndbd — The NDB Cluster Data Node Daemon” , and Section 23.3.3.6, “Defining NDB Cluster Data Nodes” , respectively. ndbmtd  is also file system-compatible with  ndbd . In other words, a data node running  ndbd  can be stopped, the binary replaced with  ndbmtd , and then restarted without any loss of data. (However, when doing this, you must make sure that  MaxNoOfExecutionThreads  is set to an apppriate value before restarting the node if you wish for  ndbmtd  to run in multithreaded fashion.) Similarly, an  ndbmtd binary can be replaced with  ndbd  simply by stopping the node and then starting  ndbd  in place of the multithreaded binary. It is not necessary when switching between the two to start the data node binary using  --initial . Using  ndbmtd  differs from using  ndbd  in two key respects: Like  ndbd ,  ndbmtd  generates a set of log files which are placed in the directory specified by  DataDir  in the  config.ini  configuration file. Except for trace files, these are generated in the same way and have the same names as those generated by  ndbd . In the event of a critical error,  ndbmtd  generates trace files describing what happened just prior to the error’ occurrence. These files, which can be found in the data node’s  DataDir , are useful for analysis of problems by the NDB Cluster Development and Support teams. One trace file is generated for each ndbmtd  thread. The names of these files have the following pattern: 1. Because  ndbmtd  runs by default in single-threaded mode (that is, it behaves like  ndbd ), you must configure it to use multiple threads. This can be done by setting an appropriate value in the  config.ini  file for the  MaxNoOfExecutionThreads  configuration parameter or the ThreadConfig  configuration parameter. Using  MaxNoOfExecutionThreads  is simpler, but ThreadConfig  offers more flexibility. For more information about these configuration parameters and their use, see Multi-Threading Configuration Parameters (ndbmtd). 2. Trace files are generated by critical errors in  ndbmtd  processes in a somewhat different fashion from how these are generated by  ndbd  failures. These differences are discussed in more detail in the next few paragraphs. 4254