[Pacemaker] spilit brain situation

[Dominik Klein]

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??

How likely is it that both succeed stonithing the other one at the same
time? Stonith is no orderly reboot. It is like pulling the power plug.
When one node (whichever it is) succeeds to shoot, then the other node
is _off_ and cannot do anything until it rebooted.

If you set the stonith action to poweroff (instead of reboot), you might
have a somewhat "save" configuration.

Regards
Dominik

> one more question , why we need to configure stonith in two node cluster. we
> can always set no-quorum policy to "suicide"  . As in both case whether we
> set stonith or we set no-quorum-policy to suicide  , both node will reset.
>  is there any extra benefit of  stonith over "no-quourm-policy=suicide"
> which i am missing.