[Linux-cluster] quorum

[Prathyush]

Any Idea ?


On Sat, Mar 23, 2013 at 3:41 PM, Prathyush <prathyush.r at gmail.com> wrote:

> I have the below scenario,
> I have made the first node down the service failover to second node,then I
> switched off second node ,service again swiched to third node,the quorum
> was not lost,it adjusted automatically
> On Mar 22, 2013 9:11 PM, "Digimer" <lists at alteeve.ca> wrote:
>
>> This is correct.
>>
>> Quorum needs "50% + 1" of the votes. So in Prathyush's cluster of 3
>> nodes/3 votes;
>>
>> 3 / 2 == 1.5 rounded up is 2.
>>
>> So once the second node shut down, quorum was lost. With quorum lost, the
>> remaining node will stop all of it's clustered services because it can no
>> longer be sure what the other nodes are doing. For example, the other two
>> nodes might turn back on, fail to connect to the one remaining node, decide
>> they have quorum and start clustered services. This would lead to a split
>> brain.
>>
>> If you want a 3-node cluster to work with just one node, consider adding
>> a quorum disk, assuming you have a SAN. This would add 2 votes to the
>> cluster. So the new math would be;
>>
>> 5/2 == 2.5 rounded up to 3.
>>
>> The quorum disk would give it's two votes to the remaining single node
>> for a total of 3 votes, thus giving it quorum and allowing it to operate on
>> it's own.
>>
>> digimer
>>
>> On 03/22/2013 03:16 AM, emmanuel segura wrote:
>>
>>> Hello
>>>
>>> If i understand well, you 3 node(3 total votes) and you poweroff 2, 3 -
>>> 2 = 1(quorum loss) remain less 50% of votes
>>>
>>> can you show your config and your log, without it's so hard help you
>>>
>>> Thanks
>>>
>>> 2013/3/22 Prathyush <prathyush.r at gmail.com <mailto:prathyush.r at gmail.com
>>> >**>
>>>
>>>     HI,
>>>
>>>
>>>     I have 3 node  cluster with 1 vote each ,and  decided to shut down
>>>     the 2 nodes for  maintenance .
>>>     When a proper power off /init 0 given to two of the nodes ,i never
>>>     loses the quorum
>>>     When i am making  force power off (switching off the power/pulling
>>>     the power cable) quorum  was lost and services failed in the third
>>> node.
>>>     why this is happening... any idea
>>>     --
>>>     /*Regards,
>>>     Prathyush*/
>>>
>>
>>
>> --
>> Digimer
>> Papers and Projects: https://alteeve.ca/w/
>> What if the cure for cancer is trapped in the mind of a person without
>> access to education?
>>
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>>
>


-- 
*Regards,
Prathyush*
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