By default, we retain FTDC data according to a fixed size limit. As we have added more metrics to FTDC over the years, this means we have implicitly shrunk the retention time window. In order to counter-act this effect, we propose increasing default retention size slightly to compensate, e.g. by 10-25%.

Since the total size is quite small (currently defaults to 200MB), this marginal increase (20-50MB as proposed) should bear little burden on customers. For sharded clusters the default is double of the normal minimum (currently 400 MB), so the new default will be 500MB.