On 12/1/12 8:48 AM, Hermes Flying wrote:
> Great help! Please allow me to trouble you with one last question.
>
> If I get this, when I use fencing and the corosync fails then linux-2 
> will attempt to crash linux-1 and take over. At this point though 
> linux-1 won't try to do anything right? Since it knows it is the 
> primary, I mean.

linux-1 will be powered off or crashed, so i think that speaks for itself.
>
> Then you say:"Any resource previously running on linux-1 will be 
> started on linux-2."
> Now at this point: By resource you mean only pacemaker and its related 
> modules, right? Because I want  Tomcat to be up and running and 
> receiving requests in Linux-2 as well, which will be forwarded by load 
> balancer of linux-1. Is this correct?

I mean 'resources managed by pacemaker'. So if you VIP was running on 
linux-1, and it fails, and linux-2 fences it, the only place the VIP can 
run is linux-2. linux-1 is totally down.
>
> Also in your setup of 2 NICs or 2 switches I assume that the idea is 
> that the probability of split-brain due to network failure is very low 
> right? Because I have read that it is not possible to avoid 
> split-brain without adding a third node. But I may be misunderstanding 
> this
A third node will eliminate split brain by definition, as quorum will 
only be obtained if a minimum of two nodes are available.

If you have a diverse network configuration and good change management, 
you're probably not going to experience a split brain unless you have a 
substantial environment failure that will probably impact your client 
ability to access anything. Since you are not running shared storage, 
you're not going to experience data loss which is typically the biggest 
concern with split brain.

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