Methods, apparatuses and computer software products implement embodiments of the present invention that include storing, to a module memory in each of a plurality of modules having multiple sub-modules, a record containing record entries corresponding respectively to the sub-modules. Upon detecting changes in respective states of the sub-modules of a given module, the corresponding record entries are set in response to the detected changes in the states of the sub-modules of the given module. A cache containing cache entries corresponding respectively to the sub-modules in the plurality of the modules is stored to a controller memory, and the record in each of the modules is polled. Upon detecting that a given record entry of the given module has been set, from the current state information with respect to the given sub-module is requested and received, and a corresponding cache entry is updated in the cache with the current state information.