Hi
i do not run server-to-server database replication
the servers doesn't speak with one another, all traffic is served for a lot of end hosts, just like a cdn would.
i do not have any special aging time out for arp configured on any interface nor on system level, so i guess they're all in default configurations.
regarding the server configs, i can't tell, those are closed boxes i don't have access to.
i guess it has something to do with switches configs, same servers with same vrrp solution (active/standby) with other switches vendors equally load balance, so i don't see how servers will age out their arp entries and perform this amound of flood & learn.