Default memory region is always there even if you add more user-defined
data regions. If you are not going to use it at all and not happy with the
memory still allocated to the default region you can specify a smaller
amount of memory allocated for the default region as described here
If I use something like the configuration example from the documentation:
| name="dataStorageConfiguration"> class="org.apache.ignite.configuration.DataStorageConfiguration">
class="org.apache.ignite.configuration.DataRegionConfiguration">
value="#{500L * 1024 * 1024}"/>
