If you retire a disk, or all of the disks on a node, that node is still available to service INFO requests to the cluster. The streams on the retiring disks also will be included in a countreps=yes request for a particular stream.
For example, if you have a freshly formatted 2 node cluster, and you write a single stream with minreps=2, the cluster will report two replicas of that stream. If you retire one of the nodes and you do another INFO with the countreps=yes option, it will continue to show 2 replicas of the stream. If you power down the retiring node, and perform the same INFO, you will see a single replica.