[Pacemaker] spilit brain situation

[Andrew Beekhof]

On Feb 6, 2009, at 11:29 AM, Priyanka Ranjan wrote:

>
>
> On Fri, Feb 6, 2009 at 3:24 PM, Andrew Beekhof <beekhof at gmail.com>  
> wrote:
>
> On Feb 6, 2009, at 10:49 AM, Romi Verma wrote:
>
>>
>>
>> On Fri, Feb 6, 2009 at 3:09 PM, Andrew Beekhof <beekhof at gmail.com>  
>> wrote:
>>
>> On Feb 6, 2009, at 10:29 AM, Romi Verma wrote:
>>
>> > i want the partition without quorum to reset the nodes instead of  
>> killing .
>> > is it possible.
>>
>> define the difference between reset node and kill node?
>>
>>  According to me  , killing a node means powering it off but  
>> reseting a node means rebooting it.
>>
>> This is controlled with the  stonith-action option
>>
>>
>> but  dont you think in two nodes cluster if we get spilit brain  
>> situation both node will try to stonith each other.
>>
>> which is why two node clusters are good for demonstrations and  
>> thats about it.
>> there are some limited uses for them, but in general you need 3  
>> nodes for a sane cluster
>>
>> so do you mean two nodes cluster are not good for production  
>> environment  because both will try to  stonith each other in spilit  
>> brain??
>
> amongst other things.
>
> even though one side wins the initial "race-to-stonith", if the  
> looser comes up again and the cause of the split-brain still  
> exists... then they'll just shoot the "winner" so it can start  
> resources... then that node comes up and shoots the other host so it  
> can start resources... etc etc
>
> ooh it's so horrible. Cant we do something to overcome this  
> situation or , we will simply suggest not to use 2 nodes cluster at  
> all.

you can set the stonith-action option to poweroff, but its still not  
ideal

>
>
>>
>>
>> one more question , why we need to configure stonith in two node  
>> cluster. we can always set no-quorum policy to "suicide"
>
> which works by using stonith
>
> wow it's interesting. i had no idea that stonith is behind this . i  
> saw some stonith devices by doing  stonith -L . so which stonith  
> device should i configure  for this.
>  is it stonith -suicide device??
>
> consider I have configured stonith in my cluster .
> if no-quorum-policy is set to "ignore"  then i guess no stonith will  
> be executed  and
>  if no-quorum-policy is set to  "suicide", "stop" or  "freeze"  then  
> stonith will be executed. Right??

no. only for suicide

>
>
>  Hey i must say this is wonderful list.  you ppl are really very  
> helpful . Thanks.
>
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