Upgrade data node (no replies)

I am the beginer of mysql cluster, i just take over a mysql cluster upgration job.In my envrionment, we have 4 data nodes with 2 group and 2 management nodes.
right now, i need to upgrade our data node to 4 new servers with more memory, what's best steps and suggestions for this upgration withou impact business?
If we need to modify data&index memory usage configuration, what's safe steps?

Thanks in advance for your help.