The wikimedia storage group containing primarily commons data has been the source of some OOM trouble from frequently re-rendered, very large gallery pages. It also sees very little use from VisualEditor or apps.
Similarly, the wikidata storage group is full of frequently edited JSON blobs. Only a very small minority of pages are actually edited in VE. For this reason, we have already disabled pre-generation for the main namespace.
To clear storage for both groups & generally get an idea of the storage savings, I am thus proposing to truncate tables for the entire wikimedia and wikidata storage groups.