Upgrading and Downgrading NDB Cluster C:\>  SC START ndb_mgmd C:\>  SC START ndbd C:\>  SC START mysql 4003 The table shown here provides information on NDB Cluster upgrade and downgrade compatibility among different releases of NDB 8.0. Additional notes about upgrades and downgrades to, from, or within the NDB Cluster 8.0 release series can be found following the table. Only compatibility between MySQL versions with regard to  NDBCLUSTER  is taken into account in this section, and there are likely other issues to be considered. As with any other MySQL software upgrade or downgrade, you are strongly encouraged to review the relevant portions of the MySQL Manual for the MySQL versions from which and to which you intend to migrate, before attempting an upgrade or downgrade of the NDB Cluster software . See Section 2.11, “Upgrading MySQL” . Schema operations, including SQL DDL statements, cannot be performed while any data nodes are restarting, and thus during an online upgrade or downgrade of the cluster. For other information regarding the rolling restart procedure used to perform an online upgrade, see Section 23.5.5, “Performing a Rolling Restart of an NDB Cluster” . This section provides information about NDB Cluster software and table file compatibility between different NDB Cluster 8.0 releases with regard to performing upgrades and downgrades as well as compatibility matrices and notes. You should already be familiar with installing and configuring NDB Cluster prior to attempting an upgrade or downgrade. See Section 23.3, “Configuration of NDB Cluster” . Important 23.2.7 Upgrading and Downgrading NDB Cluster In a production setting, it is usually not desirable to shut down the cluster completely. In many cases, even when making configuration changes, or performing upgrades to the cluster hardware or software (or both), which require shutting down individual host machines, it is possible to do so without shutting down the cluster as a whole by performing a  rolling restart  of the cluster. For more information about doing this, see Section 23.5.5, “Performing a Rolling Restart of an NDB Cluster” . •On the SQL node host ( 198.51.100.20 ), execute the following command: •On the management node host, use the  ndb_mgm  client to verify that the management node and both data nodes have started successfully (see Section 23.2.2.3, “Initial Startup of NDB Cluster on Windows” ). •On each of the data node hosts ( 198.51.100.30  and  198.51.100.40 ), execute the following command: