Very little. Stainless cable railings need only an occasional wipe-down and a periodic check of the cable tension, and quality hardware tensioned correctly at install holds for years. On a Clyde Hill view deck the main upkeep is keeping the cables and posts clean so the stainless stays bright, with none of the sealing or repainting a wood baluster railing demands. The low upkeep is part of why owners here choose cable for a deck the whole home is oriented around.