[Pacemaker] pacemaker/dlm problems

[Vladislav Bogdanov]

03.10.2011 10:56, Andrew Beekhof wrote:
> On Mon, Oct 3, 2011 at 3:34 PM, Vladislav Bogdanov<bubble at hoster-ok.com>  wrote:
>> 03.10.2011 04:41, Andrew Beekhof wrote:
>> [...]
>>>>>> If pacemaker fully finish processing of one membership change - elect
>>>>>> new DC on a quorate partition, and do not try to take over dc role (or
>>>>>> release it) on a non-quorate partition if quorate one exists, that
>>>>>> problem could be gone.
>>>>>
>>>>> Non quorate partitions still have a DC.
>>>>> They're just not supposed to do anything (depending on the value of
>>>>> no-quorum-policy).
>>>>
>>>> I actually meant "do not try to take over dc role in a rejoined cluster
>>>> (or release that role) if it was running on a non-quorate partition
>>>> before rejoin if quorate one existed".
>>>
>>> All existing DC's give up the role and a new one is elected when two
>>> partitions join.
>>> So I'm unsure what you're referring to here :-)
>>>
>>>> Sorry for confusion. Not very
>>>> natural wording again, but should be better.
>>>>
>>>> May be DC from non-quorate partition should just have lower priority to
>>>> become DC when cluster rejoins and new election happen (does it?)?
>>>
>>> There is no bias towards past DCs in the election.
>>
>>  From what I understand, election result highly depends on nodes
>> (pacemaker processes) uptime. And DC.old has a great chance to win an
>> election, just because it won it before, and nothing changed in election
>> parameters after that. Please fix me.
>
> Correct.  But its not getting an advantage because it was DC.

But it could have it because it f.e. has greater uptime (and that 
actually was a reason it won previous elections, before split-brain).
And then it can drop all cib modifications which happened in a quorate 
partition during split-brain. At least some messages in logs (you should 
have them) make me think so. If it is possible to avoid this - it would 
be great. So, from my PoV, one of two should happen
* DC.old does not win
* DC old wins and replaces its CIB with copy from DC.new

Am I wrong here?

Vladislav