[ClusterLabs] SBD fencing and crashkernel question

Roger Zhou ZZhou at suse.com
Mon Oct 21 06:09:35 EDT 2019

On 10/20/19 7:03 AM, Strahil Nikolov wrote:
> Hello Community,
> I have a question about the stack in newer version compared to our SLES 
> 11 openais stack.
> Can someone clarify if a node with SBD will invoke a crashkernel before 
> self killing ?
> According to my tests on SLES 11 ,when another node kills the 
> unresponsive one - crashkernel is invoked and a dump is present at 
> /var/crash , but if the node stucks for some reason (naughty admin) - 
> there is no sign of a crash (checked on the iLO to be sure).

"crashdump" is one of SBD option need be configured on purpose.

You can `man sbd` to check the "-r" option, or "SBD_TIMEOUT_ACTION" in 

> I'm not sure if this behaviour is the same on newer software version 
> (SLES 12/15) and if I can workaround it - as we still struggle to find 
> the reason why our clusters fence on a very specific situation (the 
> clusters are using MDADM raid1-s on a dual-DC environment instead of SAN 
> replication) where remote DC is unavailable for 20-30s until SAN/Network 
> is rerouted.

Not sure if you imply cluster-md-raid1 here?
If yes, you might refer to Page 18 of [1](

> We have enabled crashdump on some of the systems , but we 
> are pending a reboot and then a real DC<->DC connectivity outage to 
> gather valuable info,as corosync is using dual-rings and is not 
> affected, SBD is using survive on pacemaker and we suspect that the 
> nodes suicide.

Not able to follow up all your words, you might want to rephrase with a 
bit more details.


> Best Regards,
> Strahil Nikolov
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