I have found that for members of a user group with a group of groups limitation on it they are unable to view interface and volume stats for nodes in groups they have access to. The last time I came across this, only Volumes were hidden, they could see the stats for interfaces on nodes they had permission to view. It appears that has been "fixed" now and neither volumes nor interfaces are visible to these users. The fix I was give previously was to add each of the Volumes to a group that the user group was allowed access to. At that time, when it was limited to volumes it was a major pain and resulted in scalability issues. Now that it appears interfaces are also excluded unless specifically allowed that increases the headache and scalability problem.
My question. Is there a better way to grant members of a group of groups limited users group visibility into interfaces and volumes on nodes they have permission to view without manually adding each volume or interface to a group?