[Pacemaker] Few questions

[Andrew Beekhof]

On Feb 9, 2009, at 1:03 PM, Romi Verma wrote:

>
>
> On Mon, Feb 9, 2009 at 5:01 PM, Andrew Beekhof <beekhof at gmail.com>  
> wrote:
>
> On Feb 9, 2009, at 12:25 PM, Romi Verma wrote:
>
>>
>>
>> On Mon, Feb 9, 2009 at 4:04 PM, Andrew Beekhof <beekhof at gmail.com>  
>> wrote:
>> On Feb 9, 2009, at 11:21 AM, Dejan Muhamedagic wrote:
>>
>> On Mon, Feb 09, 2009 at 03:09:40PM +0530, Romi Verma wrote:
>>
>>
>> sorry to interrupt in between. just one question from my side.  if
>> no-quorum-policy is set to freeze then resource is not supposed to  
>> stop .
>>
>> right.
>>
>> in
>> that case node will not be fenced right??
>>
>> no-quorum-policy has nothing to do with fencing.
>>
>> well, depending on what it's set to, it can prevent fencing (no- 
>> quorum-policy != ignore) or cause it to be initiated when quorum is  
>> lost (no-quorum-policy == suicide)
>>
>> but if you're using freeze, and a resource must stop for other  
>> reasons but fails to, then the node will not be shot (although it  
>> probably should be).
>>
>> Thanks Andrew,
>>
>> in case of more then 2 nodes we cant use no-quorum-policy to   
>> "ignore" as we cant just ignore quourum. as you said in case of  
>> freeze node will not be fenced.
>
> right, but thats a good thing.
> It only applies if you have an even split (ie. 2-2) where no-one has  
> quorum.
> you only want to fence if you plan on taking over the other side's  
> resources - which freeze wont do.
>
> if you get a 3-1 split, then the side that has quorum _will_ shoot  
> the 1 node and take over its resources.
>
>
> ook wow,  it means if i have set no-quorum-policy to "ignore" it can  
> be used in more than 2 nodes also.
> if it  is 2-2 split then both  partitons will try to stonith each  
> other (.to get rid of this as you said  we have to set stonith- 
> action=powerfail or will not have to remove openais from startup  
> service so that it cant get executed once the node comes up.)
>
> and if we get 3-1 spilit then automatically the partion having 3  
> nodes will stonith the 1 node.

almost, if you use ignore, the 1 will also try to shoot the 3.

this is why freeze is safer, it:
* keeps running anything it can
* doesn't start anything belonging to the other partition unless it  
has quorum
* won't try to shoot the other side except if it has majority
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