i can’t find any docs on how to do this
Did you try under the namespace config?
Following the example on this page: Cluster Configuration Settings | Aerospike Documentation, I would expect it to simply be as follows (namespace level configuration parameter):
namespaces:
- name: test
memory-size: 3000000000
nsup-period: 120
replication-factor: 2
storage-engine:
type: memory
Did this not work? (I didn’t try it, just guessing from the config example).