Since it's somewhat reasonable to place one of the config servers into Disaster Recovery Zone (which has high latency), the metadata upgrade procedure can take a very long time because of the high network latency.

For the config database with a large number of chunks (100k), the upgrade process can take many many hours (6+) when latency to one of the config servers is seconds. (We have seen it take 30-40 min all config servers are within milliseconds ping with that large number of chunks)

We should be able to display a warning (esp. during the upgrade process) if we detect that ping time to the config servers, or any config server relative to the other(s), is too high.