21.3.6 Safe Shutdown and Restart of NDB Cluster

To shut down the cluster, enter the following command in a shell on the machine hosting the management node:

$> ndb_mgm -e shutdown

The -e option here is used to pass a command to the ndb_mgm client from the shell. The command causes the ndb_mgm, ndb_mgmd, and any ndbd or ndbmtd processes to terminate gracefully. Any SQL nodes can be terminated using mysqladmin shutdown and other means. On Windows platforms, assuming that you have installed the SQL node as a Windows service, you can use SC STOP service_name or NET STOP service_name.

To restart the cluster on Unix platforms, run these commands:

On the management host (198.51.100.10 in our example setup):
```
$> ndb_mgmd -f /var/lib/mysql-cluster/config.ini
```
On each of the data node hosts (198.51.100.30 and 198.51.100.40):
```
$> ndbd
```
Use the ndb_mgm client to verify that both data nodes have started successfully.
On the SQL host (198.51.100.20):
```
$> mysqld_safe &
```

On Windows platforms, assuming that you have installed all NDB Cluster processes as Windows services using the default service names (see Section 21.3.2.4, “Installing NDB Cluster Processes as Windows Services”), you can restart the cluster as follows:

On the management host (198.51.100.10 in our example setup), execute the following command:
```
C:\> SC START ndb_mgmd
```
On each of the data node hosts (198.51.100.30 and 198.51.100.40), execute the following command:
```
C:\> SC START ndbd
```
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 21.3.2.3, “Initial Startup of NDB Cluster on Windows”).
On the SQL node host (198.51.100.20), execute the following command:
```
C:\> SC START mysql
```

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 21.6.5, “Performing a Rolling Restart of an NDB Cluster”.