From d5f45714b0a82686b3af1738f66f0a3491b7f938 Mon Sep 17 00:00:00 2001 From: Bela Ban Date: Tue, 2 Oct 2012 16:23:44 +0200 Subject: [PATCH] Added section on RELAY2.can_become_site_master --- doc/manual/en/modules/advanced.xml | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/doc/manual/en/modules/advanced.xml b/doc/manual/en/modules/advanced.xml index b92f5c53746..43a8dcfe443 100644 --- a/doc/manual/en/modules/advanced.xml +++ b/doc/manual/en/modules/advanced.xml @@ -2028,6 +2028,23 @@ On view change V: site master of LON. If the site master changes, messages will get relayed to a different node, which took over the role of the site master from the old (perhaps crashed) site master. + + Sometimes only certain members of a site should become site masters; e.g. the more powerful boxes + (as routing needs some additional CPU power), or multi-homed hosts which are connected to the external + network (over which the sites are connected with each other). + + + To do this, RELAY2 can generate special addresses which contain the knowledge about whether a member + should be skipped when selecting a site master from a view, or not. If can_become_site_master is + set to false in RELAY2, then the selection process will skip that member. However, if all members in + a given view are marked with can_become_site_master=false, then the first member of the view will + get picked. + + + When we have all members in a view marked with can_become_site_master=false, e.g. {B,C,D}, then B + is the site master. If we now start a member A with can_become_site_master=true, then B will stop + being the site master and A will become the new site master. +