The XMS talks to a component on the storage controllers called the "System Manager", or SYM for short.  The SYM only ever runs on a single storage controller at a time, but can move between the two storage controllers in the first brick in the array, so if a storage controller fails for any reason, the SYM will nearly immediately move to the other SC so that the XMS can still communicate with it.  Specifically for configuration events, the SYM can then push details to all of the other storage controllers in the array, which occurs over the InfiniBand backplane of the array.
In a multi Xbrick XtremIO Cluster, how does the xms push the control configs to storage controllers? Does it randomly pick one SC to do the config or it picks SCs in a RR fashion?
XMS communication to storage controllers