Perhaps this has already been addressed but we have always observed that 3.x clusters would need to have their process memory limit in /etc/foundationdb/foundationdb.conf increased beyond 8G (we have 10G for a cluster that has 30+TB of KVs (100+TB on disk). Perhaps at that size the recommendation would be to always have separate transaction processes.
Perhaps this has already been addressed but we have always observed that 3.x clusters would need to have their process memory limit in /etc/foundationdb/foundationdb.conf increased beyond 8G (we have 10G for a cluster that has 30+TB of KVs (100+TB on disk). Perhaps at that size the recommendation would be to always have separate transaction processes.