How to rescan FC multipath on linux?

Question

CentOS

Good afternoon!
the people who faced such task?
There is a storage shelf. through sanswitch several servers are connected to it via FC.
everything is working. 4 paths go to each moon, two through one controller, two through another. respectively two active ready running, two active ghost running.
when simulating a situation with a dump (fall, reboot) of one controller, all paths move to a spare one. at the same time, two paths from the server disappear, i.e. multipath -ll gives only two paths to the moon instead of four. But! after the controller is restored, the two missing paths are not restored. they will be restored if you do a restart multipathd, but there must be a human way to rescan the paths. I can't restart it with a cron every 5 minutes.