Change 123243 had a related patch set uploaded by Chad:
Set mw_cirrus_versions to have no replicas

https://gerrit.wikimedia.org/r/123243

Change 123243 merged by jenkins-bot:
Set mw_cirrus_versions to have no replicas

https://gerrit.wikimedia.org/r/123243

You'll need to manually lower/raise the existing replica settings (or blow away mw_cirrus_versions and rebuild it). The default's no replicas now so should be fine for all installs going forward though.

Great, I will try it in the next days... Thank you!

I now just deleted the "mw_cirrus_versions" and everything seems to work. And ElasticSearch is "green" again ;-)
Thank you guys...