org.apache.ignite.internal.managers.discovery.GridDiscoveryManager#requiredOffheap calculate size of system and configured data regions 2 times.
org.apache.ignite.internal.processors.cache.persistence.GridCacheDatabaseSharedManager#getDataStorageConfiguration initialize assign 2 variable by getDataStorageConfiguration result
When data regions are not configured org.apache.ignite.internal.processors.cache.persistence.GridCacheDatabaseSharedManager#checkpointBufferSize get DataStorageConfiguration.DFLT_DATA_REGION_MAX_SIZE constant instead of maximum size of default data region.