Load balanced php servers best practice

Hi,

I’m wondering what the best approach is to take if there are multiple PHP servers behind a load balancer being used to serve WordPress. Should each PHP server have its own Redis node, or is it better to use a single Redis cache db server for all servers?

Take for example an HA Proxy sitting in front of multiple hosts, each has WP running on clustered file storage & clustered MariaDB database. Should each host have a Redis DB of its own, that the WP application uses? Or should there be a single Redis node (I’m not quite at the point of going full Redis cluster) which all hosts connect to from the WP application?

Thanks in advance!