This is the configured maximum size allotted to the SmartEvent events database. This is the ceiling an admin compares the current database size against to know how much headroom remains before old events start getting purged or new events stop being logged, which directly affects how far back historical incident investigation can reach. For example, a capacity of 50 gigabytes with current size at 47 gigabytes would mean the admin has only days left before the oldest events start rolling off.