I'd not be concerned so much about growth if it's on the larger volume. I don't expect it to grow quickly once it's populated with all the deps we need. Basically, snapshots are added, but those shouldn't take huge amounts of space. So we may sustain on the other volume for quite a while, but yes, pruning it regularly would be nice. Weekly, monthly, something like that

The "/var/log/journal" issue is real, I manually reduced it on cislave-3. This should be done in the Ansible set-up to keep it on something like 100 MB max or so.

The JDK install is another one, there seem to be several versions of the same major (e.g. I could remove one 8 and one 9 IIRC), I suppose some installed via Ansible, some through Jenkins JDK auto-installs. It would be nice to consolidate that, but it requires some analysis of what's actually needed. Ideally, there is just one 7, 8, 9 and that's it. Btw. see the answer to this question on SO, it provides a nice way for analyzing which JDKs are actually used by which jobs.