[ClusterLabs] Pacemaker Fail Master-Master State

İsmet BALAT bcalbatros at gmail.com
Sun Feb 21 04:45:38 EST 2021


I am testing aşk scenarios because I will use real machines with pacemaker.
Scenarios;

1-
node1  master
node2 slave
Shutting node1, then node2 become master
Successfully

2-
node1  slave
node2 master
Shutting node2, then node1 become master
Successfully

3-
node1  slave
node2 slave
One node become master after 60s
Successfully

4-
node1  master
node2 master
First machine fail, and not fix unlike send command cleanup
Fail

I haven’t got physical fencing device. But all machines must online for
redundancy. So I guess we don’t use fencing. Because servers havent got
connection for remote help and internet. They must fix their:)



On 21 Feb 2021 Sun at 12:14 damiano giuliani <damianogiuliani87 at gmail.com>
wrote:

> My question is:
> Why you are pausing one VM?there is any specific scope in that?you should
> never have 2 master resources, pausing one vm could make unexpected
> behaviours.
> If you are testing failovers or simulated faults you must configure a
> fencing mechanism.
> Dont expect your cluster is working properly without it.
>
> On Sun, 21 Feb 2021, 07:29 İsmet BALAT, <bcalbatros at gmail.com> wrote:
>
>> Sorry, I am in +3utc and was sleeping. I will try first fix node, then
>> start cluster. Thank you
>>
>> On 21 Feb 2021 Sun at 00:00 damiano giuliani <damianogiuliani87 at gmail.com>
>> wrote:
>>
>>> resources configured in a master/slave mode
>>> If you got 2 masters something is not working right. You should never
>>> have 2 node in master.
>>> Disable pacemaker and corosync services to autostart on both nodes
>>> systemctl disable corosync
>>> Systemctl disable pacemaker
>>>
>>> You can start the faulty node using pcs cli:
>>> pcs cluster start
>>>
>>> You can start the whole cluster using
>>> pcs cluster start --all
>>>
>>> First of all configure a fencing mechanism to make the cluster
>>> consistent. Its mandatory.
>>>
>>>
>>>
>>> On Sat, 20 Feb 2021, 21:47 İsmet BALAT, <bcalbatros at gmail.com> wrote:
>>>
>>>> I am not using fence. If I disable pacemaker,how node join cluster (for
>>>> first example in video - master/slave changing)? So I need a check script
>>>> for fault states :(
>>>>
>>>> And thank you for reply
>>>>
>>>> On 20 Feb 2021 Sat at 23:40 damiano giuliani <
>>>> damianogiuliani87 at gmail.com> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> Have you correcly configure a working fencing mechanism?without it you
>>>>> cant rely on a safe and consistent environment.
>>>>> My suggestion is to disable the autostart services (and so the
>>>>> autojoin into the cluster) on both nodes.
>>>>>  if there is a fault you have to investigate before you rejoin the old
>>>>> fault master node.
>>>>> Pacemaker (and paf if u are using it) as far i know,  doesnt support
>>>>> the autoheal of the old master, so you should resync or pg_rewind eveythime
>>>>> there is a fault.
>>>>>
>>>>>
>>>>>
>>>>> On Sat, 20 Feb 2021, 19:03 İsmet BALAT, <bcalbatros at gmail.com> wrote:
>>>>>
>>>>>> I am using Pacemaker with Centos 8 and Postgresql 12. Failover
>>>>>> master/slave states successfully run. But if all nodes are masters,
>>>>>> pacemaker can't repair its unlikely send command 'pcs resources cleanup'.
>>>>>> Wheras I set 60s in resource config. How can I fix it?
>>>>>>
>>>>>> StackOverFlow link:
>>>>>> https://stackoverflow.com/questions/66292304/pacemaker-postgresql-master-master-state
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>> İsmet BALAT
>>>>>>
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