One thing that I have noticed is that if your hosts are getting close to be maxed out memory wise, Rancher starts moving containers that no longer fit on one host to another, which is all good.
But if all hosts are high on memory utilization, containers seems to be ping ponging back and forth between hosts.
This is of course a user issue, but I still think it would be quite nice to have Rancher monitor that sort of behavior and maybe indicate this some how. Some kind of “running hot” indicator for hosts would be nice.
My 2 cents