On 10/02/16 02:40 AM, Ulrich Windl wrote: >>>> Digimer <li...@alteeve.ca> schrieb am 08.02.2016 um 20:03 in Nachricht > <56b8e68a.1060...@alteeve.ca>: >> On 08/02/16 01:56 PM, Ferenc Wágner wrote: >>> Ken Gaillot <kgail...@redhat.com> writes: >>> >>>> On 02/07/2016 12:21 AM, G Spot wrote: >>>> >>>>> Thanks for your response, am using ocf:pacemaker:controld resource >>>>> agent and stonith-enabled=false do I need to configure stonith device >>>>> to make this work? >>>> >>>> Correct. DLM requires access to fencing. >>> >>> I've ment to explore this connection for long, but never found much >>> useful material on the subject. How does DLM fencing fit into the >>> modern Pacemaker architecture? Fencing is a confusing topic in itself >>> already (fence_legacy, fence_pcmk, stonith, stonithd, stonith_admin), >>> then dlm_controld can use dlm_stonith to proxy fencing requests to >>> Pacemaker, and it becomes hopeless... :) >>> >>> I'd be grateful for a pointer to a good overview document, or a quick >>> sketch if you can spare the time. To invoke some concrete questions: >>> When does DLM fence a node? Is it necessary only when there's no >>> resource manager running on the cluster? Does it matter whether >>> dlm_controld is run as a standalone daemon or as a controld resource? >>> Wouldn't Pacemaker fence a failing node itself all the same? Or is >>> dlm_stonith for the case when only the stonithd component of Pacemaker >>> is active somehow? >> >> DLM is a thing onto itself, and some tools like gfs2 and clustered-lvm >> use it to coordinate locking across the cluster. If a node drops out, >> the cluster informs dlm and it blocks until the lost node is confirmed >> fenced. Then it reaps the lost locks and recovery can begin. >> >> If fencing fails or is not configured, DLM never unblocks and anything >> using it is left hung (by design, better to hang than risk corruption). >> >> One of many reasons why fencing is critical. > > I'm not deeply in DLM, but it seems to me DLM can run standalone, or in the > cluster infrastructure (we only use it inside the cluster). When running > standalone, it makes sense that DLM has ist own fencing, but when running > inside the cluster infrastructure, I'd expect tha tthe cluster's fencing > mechanisms are used (maybe just because if the better logging of reasons).
To be clear; DLM does NOT have it's own fencing. It relies on the cluster's fencing. -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education? _______________________________________________ Users mailing list: Users@clusterlabs.org http://clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org