Ceph » RADOS

In http://docs.ceph.com/docs/jewel/rados/operations/crush-map/ this section is the closest thing to documenting the impact on connected clients after updating the tunables.

"The ceph-osd and ceph-mon daemons will start requiring the feature bits of new connections as soon as they get the updated map. However, already-connected clients are effectively grandfathered in, and will misbehave if they do not support the new feature."

This section could be clarified to warn that clients will stop functioning completely. This section is also buried far down the document and not in an obvious location in the document to warn of the impact of modifying tunables. Sections earlier in the document talk about data migration and performance impacts. Perhaps the warning about client connectivity should be included near these sections on impacts.