AEM sites that include AEM Communities features (community sites) experience a high level of interaction from site visitors (members) in the publish environment.
The sizing considerations for a community site depends on the anticipated interaction by community members and whether optimal performance for page content is of higher importance.
User generated content (UGC), submitted by members, is stored separately from page content. While the AEM platform uses a node store that replicates site content from author to publish, AEM Communities uses a single, common store for UGC that is never replicated.
For the UGC store, it is necessary to choose a storage resource provider (SRP), which influences the chosen deployment.