I have noticed that none data node still allocates half of system RAM.
Wouldn't it make more sense to allocate more RAM for ES heap in such node?
We don't really need to leave too much RAM for the system since there's no file caching.
My node has 32GB of RAM and ES takes about 15GB with the default auto config.
In our old 7.3.1 cluster, we manually allocate 25GB of RAM for ES heap and leave the rest about 7GB for system and it runs fine.