You display system statistics on a server-switch using the system-stats-show command:
CLI network-admin@@Leaf1>system-stats-show layout vertical
The swap-scan output displays the number of scans performed on the swap. A nonzero number indicates that memory is paged from the physical memory (RAM) to virtual memory (disk or swap). A consistently high value indicates that all memory, both physical and virtual, is exhausted and the system may stop responding.