Thank you for your help. I take it that you are find Pacemaker reliable in your experience? Should I look into it?
________________________________ From: David Coulson <[email protected]> To: Hermes Flying <[email protected]> Cc: Baptiste <[email protected]>; "[email protected]" <[email protected]> Sent: Thursday, November 29, 2012 11:04 PM Subject: Re: HAproxy and detect split-brain (network failures) Again, you need to talk to the pacemaker people for actual clustering information. The ping was so a node could detect it lost upstream connectivity, and move the VIP, otherwise the VIP may continue to run on a system which does not have access to your network. This has nothing at all to do with split brain. If you want to deal with split brain, add a third node. Period. You also want to have redundant heartbeat communication paths. You also want STONITH/fencing so if one node detects the other is down it'll power it off or crash it. I've not had issues with a two-node cluster with two diverse backend communication links and fencing enabled. David On 11/29/12 3:58 PM, Hermes Flying wrote: "You can have pacemaker ping an IP (gateway for example) and migrate the VIP based on that" >How does this help for splitbrain? >If I understand what you say, pacemaker will ping an IP and if successfull >will assume that the other node has crashed. But what if the other node hasn't >and it is just their communication link that failed? Won't both become >primary? >How does the ping help? > > > >From: David Coulson mailto:[email protected] >To: Hermes Flying mailto:[email protected] >Cc: Baptiste mailto:[email protected]; mailto:[email protected] >mailto:[email protected] >Sent: Thursday, November 29, 2012 10:26 PM >Subject: Re: HAproxy and detect split-brain (network failures) > > > > >On 11/29/12 3:11 PM, Hermes Flying wrote: > >I see now! >>One last question since you are using Pacemaker. Do you recommend it for splitbrain so that I look into that direction? >> >Any two node cluster has risk of split brain. if you implement fencing/STONITH, you are in a better place. If you have a third node, that's even better, even if it does not actually run any services beyond the cluster software > >I mean when you say that pacemaker restart HAProxy, does it detect network >failures as well? Or only SW crashes? >>I assume pacemaker will be aware of both HAProxy1 and HAProxy2 in my described deployment >> You can have pacemaker ping an IP (gateway for example) and migrate the VIP based on that. In my config I have haproxy configured as a cloned resource in pacemaker, so all nodes have the same pacemaker config for haproxy and it keeps haproxy running on all nodes all of the time. > > >
