Cluster openvas Master/Slave

Hello everyone,
I’m build a cluster of openvas because I want more performance in my environment of type; each slave scan one sub net.

My project w’l be running on openshifit. I’m search in internet for some docker file ready for use, in this searching I found the architecture bellow .

(https://www.nopsec.com/wp-content/uploads/openvas-cluster_arch.width-800-600x496.png)

I’ve one question about this architecture, why each slave should have one redis and one postgres dedicated?

I want use only 1 redis and one postgres for all environment, it’s possible? Bellow link of this architecture with reference .

Link nopsec: https://www.nopsec.com/docker-based-openvas-scanning-cluster-to-improve-scope-scalability/