[Pacemaker] spilit brain situation

[Romi Verma]

On Fri, Feb 6, 2009 at 2:28 PM, Andrew Beekhof <beekhof at gmail.com> wrote:

>
> On Feb 6, 2009, at 9:53 AM, Romi Verma wrote:
>
> Thanks Dominic,
> i have two questions now.
>
> 1) what does no-quorum-policy= suicide means then??  does it remove the
> resource completely.
>
>
> no, the node kills itself and any other node in the partition
> this makes no sense in a 2 node cluster because both nodes will do this
>

i assume the partition having less nodes will loose quorum and if
no-quorum-policy is set to suicide  then then they will commit suicide.
 like if in 3 nodes cluster , if one node looses communication to other
nodes then there will be two partitions . one will contain 2 nodes and
second will contain 1 node. partition having 2 nodes will be having quorum
and will not be affected. partition having 1 node will loose quourm and and
it will kill itself.  is my understanding is right??

i want the partition without quorum to reset the nodes instead of killing .
is it possible.

>
>
>
> 2) why each node is thinking itsef as DC as Andrew said after spilit brain
> election happens and one node is selected as DC.
>
>
> no, i said after the split-brain is _repaired_ an election occurs.
> clearly this can't happen during a split-brian because by definition they
> can't communicate.
>

ok got it  , so how do we repair this spilit brain condition . by setting
no-quorum-policy to reset??  or is there any other way also.

>
> This is not happening in my case.
> i dont have any stonith configured in my cluster . do i need stonith to
> handle spilit brain situation.
>
>
>
> On Fri, Feb 6, 2009 at 1:59 PM, Dominik Klein <dk at in-telegence.net> wrote:
>
>> Romi Verma wrote:
>> > Thanks for fast reply ,
>> > Ok, Let me explain the situation. i have two nodes cluster . i pulled
>> out
>> > the network cable of one
>> > node which produced spilit brain situation. this time both nodes are
>> > thinking that other one is dead.  each node is thinking itself as DC and
>> on
>> > each node cluster is up and running without quorum.
>> >
>> > i am new to openais/pacemaker so dont know much but according to some
>> > documents it seems by default no-quorum-policy is  to "stop" the
>> cluster. i
>> > have not specified any no-quorum-policy that's why i expect that my
>> cluster
>> > should stop if it looses quorum somehow.
>>
>> The "stop" refers to the resources. policy=stop on a node with no quorum
>> means: do not run any resources.
>>
>> "ignore" would mean: run resources even though we don't have quorum
>> (like the old heartbeat behaviour would be)
>>
>> "freeze" would mean: run and manage what you did run up to this point,
>> but don't aquire any other resources.
>>
>> Regards
>> Dominik
>>
>> > But in present spilit brain situation , on each node cluster is up and
>> > running without quorum.   could you please explain why this is
>> happening.
>> >
>> > Romi
>> >
>> >
>> > On Fri, Feb 6, 2009 at 12:52 PM, Andrew Beekhof <beekhof at gmail.com>
>> wrote:
>> >
>> >> Well the no-quorum-policy option applies during the split and an
>> election
>> >> is held to determine the DC when the partitions reform.
>> >> Can you be more specific please?
>> >> On Feb 6, 2009, at 4:54 AM, Romi Verma wrote:
>> >>
>> >>
>> >>
>> >> hi all,
>> >>> how does openais + pacemaker (suse 11) cluster handles spilit brain
>> >>> situation .  can any one explain.
>> >>>
>> >>> Thanks,
>> >>> Romi.
>> >>>
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