[ClusterLabs] Antw: Re: When the DC crmd is frozen, cluster decisions are delayed infinitely

[Klaus Wenninger]

On 09/08/2016 11:51 AM, Shermal Fernando wrote:
> Hi Jehan-Guillaume,
>
> Sorry for disturbing you. This is really important for us to pass this test on the pacemaker resiliency and robustness. 
> To my understanding, it's the pacemakerd who feeds the watchdog. If only the crmd is hung, fencing will not work. Am I correct here?

sbd is observing pacemaker (basically by interfering with corosync and
reading the cib - both
obviously not affected by your test-scenario) and is feeding the
watchdog if everything seems ok.

>
> Regards,
> Shermal Fernando
>
>
>
>
>
>
>
> -----Original Message-----
> From: Jehan-Guillaume de Rorthais [mailto:jgdr at dalibo.com] 
> Sent: Thursday, September 08, 2016 3:12 PM
> To: Shermal Fernando
> Cc: Cluster Labs - All topics related to open-source clustering welcomed
> Subject: Re: [ClusterLabs] Antw: Re: When the DC crmd is frozen, cluster decisions are delayed infinitely
>
> On Thu, 8 Sep 2016 08:58:15 +0000
> Shermal Fernando <shermalfe at millenniumit.com> wrote:
>
>> Hi Jehan-Guillaume,
>>
>> Does this means watchdog will serf-terminate the machine when the crm 
>> daemon is frozen?
> This means that if the machine is under such a load that PAcemaker is not able to feed the watchdog, the watchdog will fence the machine itself.
>
>> -----Original Message-----
>> From: Jehan-Guillaume de Rorthais [mailto:jgdr at dalibo.com]
>> Sent: Thursday, September 08, 2016 12:52 PM
>> To: Digimer
>> Cc: Cluster Labs - All topics related to open-source clustering 
>> welcomed
>> Subject: Re: [ClusterLabs] Antw: Re: When the DC crmd is frozen, 
>> cluster decisions are delayed infinitely
>>
>> On Thu, 8 Sep 2016 15:55:50 +0900
>> Digimer <lists at alteeve.ca> wrote:
>>
>>> On 08/09/16 03:47 PM, Ulrich Windl wrote:
>>>>>>> Shermal Fernando <shermalfe at millenniumit.com> schrieb am
>>>>>>> 08.09.2016 um
>>>>>>> 06:41 in
>>>> Nachricht
>>>> <8CE6E8D87F896546B9C65ED80D30A4336578CB4A at LG-SPMB-MBX02.lseg.stockex.local>:
>>>>> The whole cluster will fail if the DC (crm daemon) is frozen due 
>>>>> to CPU starvation or hanging while trying to perform a IO operation.
>>>>> Please share some thoughts on this issue.
>>>> What is "the whole cluster will fail"? If the DC times out, some 
>>>> recovery will take place.
>>> Yup. The starved node should be declared lost by corosync, the 
>>> remaining nodes reform and if they're still quorate, the hung node 
>>> should be fenced. Recovery occur and life goes on.
>> +1
>>
>> And fencing might either come from outside, or just from the server 
>> itself using watchdog.
>
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