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Re: [Linux-cluster] Dependency graphs, order of startup and failover handling

Thanks for clarifying those issues for me. I was hopping that dependency graphs would be possible with the current version. Are the dependency changes, that you are working on currently, to be included in the RHEL4? 

Unfortunately since the planned cluster will run mission critical systems everything installed should be officially supported by RedHat hence if it is not part of RHEL4 then I cannot recommend it. On the other hand I would love to try it out ;) The dependencies involved in our system are rather complex and would be a nice proving ground.

What worries me though is this

"Fencing in a two node cluster according to the FAQ could lead to each node trying to fence each other resulting in total cluster blowup. The suggested solution of that problem was to use serialized fencing devices. From my understanding the above scenario can occur because in a two node environment each node has 1 vote so there is no way to break the tie. In any case in a total unrelated section it is mentioned that a quorum disk can be used to break the tie. Well I am a bit confused since in the section it was mentioned that quorum disk support was initially removed from RHEL4 but then was added optionally. What is the proper way to create a two node cluster ? Is quorum disk required if a serialized fence device is used? Will quorum disks usage be phased out in the future ? If yes how do you plan to address the issues in a 2 node cluster?"

Thanks again,

On 12/8/06, Lon Hohberger <lhh redhat com> wrote:
On Fri, 2006-12-08 at 13:08 -0500, Lon Hohberger wrote:

> Application of those operations and running it through graphviz (dot)
> yields the attached png as a result.
> (come on, you gotta run it through graphviz!)

Note: I hope to fix the big remaining bug in the algorithm soon; maybe
early next week, and commit the test program to CVS.  Integration will
take some time, and I'm need to document "how this works" reasonably

-- Lon

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