instNodes :: ConfigData -> Instance -> S.Set String
instNodes cfg inst = maybe id S.insert (instPrimaryNode inst)
                      $ instDiskNodes cfg inst
instNodes :: ConfigData -> Instance -> S.Set String
instNodes cfg inst = maybe id S.insert (instPrimaryNode inst)
                      $ instDiskNodes cfg inst
instNodes cfg inst = maybe id S.insert (instPrimaryNode inst)
                      $ instDiskNodes cfg inst