[ClusterLabs] Antw: DLM hanging when corosync is OK causes cluster to hang

Ulrich Windl Ulrich.Windl at rz.uni-regensburg.de
Tue Jan 12 02:20:37 EST 2016

>>> Digimer <lists at alteeve.ca> schrieb am 11.01.2016 um 17:59 in Nachricht
<5693DF77.7000506 at alteeve.ca>:
> Hi all,
>   We hit a strange problem where a RAID controller on a node failed,
> causing DLM (gfs2/clvmd) to hang, but the node was never fenced. I
> assume this was because corosync was still working.

I would guess that when I/O hangs, DLM is still happy, thus there should be no fencing. Something has to time out to let the cluster become active. >From your description it's not obvious which disks were affected. I can imagine that if every local disk came to a stop, even fencing won't succeed (if triggered locally).

>   Is there a way in rhel6/cman/rgmanager to have a node suicide or get
> fenced in a condition like this?

I guess you would need a monitor for disk I/O. I wonder what would happen if you use sbd on a local (not shared disk). Maybe it will detect if that disk is not responding and reset via watchdog (if available).


> -- 
> Digimer
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