Split Brain prevention

Amir Dafny-Man <[email protected]>
Newsgroups gmane.linux.keepalived.devel
Message-ID <[email protected]>
Hi,

While integrating keepalived I encountered a split-brain situation which I understand is inherent in keepalived. I am currently trying to find a solution that does not involve code changes to keepalived.
My configuration is as follows:

-          Multiple networks: bond0 for unicast and bond2.563 for VIP

-          Same weight and state (BACKUP) for both nodes so that failback will not occur
My experience is that preventing unicast traffic between the nodes changes the node that is in BACKUP state to MASTER state and brings up the VIP on both nodes.
This is especially important as there are differnet networks for VRRP and for VIP.
I understand that keepalived sends VRRP advertisements only over the interface specified.  I think that advertising and listening on more than one interface may assist in preventing split-brain.
Pertaining to my use-case where VRRP advertisements cannot pass between the hosts but access between the nodes on the interface that holds the VIP, can keepalived check for the existence of a VIP it is about to setup prior to the actual setup itself? E.g. using arping.
I assume that notify scripts are not appropriate for this as they run after the state change.

Another point is that each node does not monitor its VIPs. That is a VIP may be taken down (e.g. ip addr del ...) and keepalived continues to function as if it is still up. I think that monitoring ip configuration made by keepalived (ips and routes) will add to the robustness of keepalived.

Thanks,
Amir Dafny-Man | System Architect
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