DISCLAIMER : Not SCMCDBA Certified
If you plan to hold data in memory, you need to
- increase RAM on all data nodes to 16GB
- increase the DataMemory to 6GB
- increase the number of SQL nodes to 3 (Makes SQLNodes to DataNodes 1:1)
If you cannot make these changes, then you should offload data to local storage
Here is one of the best answers from Frazer Clement : MySQL Cluster RAM requirement
He states in his answer
When configuring DataMemory and IndexMemory, it is best to limit yourself to somewhat less than the physical memory in each system. Some physical memory should be reserved for the OS and other processes.
There are three MySQL Cluster Gurus in this forum
Checks out their answers !!!