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

Ulrich Windl Ulrich.Windl at rz.uni-regensburg.de
Thu Sep 8 08:28:13 EDT 2016

>>> Klaus Wenninger <kwenning at redhat.com> schrieb am 08.09.2016 um 09:13 in
Nachricht <4c828344-44da-1d93-b43f-a305cfaa5402 at redhat.com>:
> On 09/08/2016 08:55 AM, Digimer 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.
> Didn't happen in my test (SIGSTOP to crmd).
> Might be a configuration mistake though...
> Even had sbd with a watchdog active (amongst
> other - real - fencing devices).
> Thinking if it might make sense so tickle the
> crmd-API from sbd-pacemaker-watcher ...

OK, so we mix "DC" and crmd. crmd is just a part of the DC. I guess if corosync is up and happy, but crmd is silent, the cluster just thinks that the DC has nothing to say.
But I still wonder what will happen if crmd is goinf to send some reply to a command.

>> Unless you don't have fencing, then may $deity of mercy. ;)
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