[ClusterLabs] GFS and cLVM fencing requirements with DLM

Ferenc Wágner wferi at niif.hu
Tue Mar 15 14:12:53 EDT 2016


I'm referring here to an ancient LKML thread introducing DLM.  In
http://article.gmane.org/gmane.linux.kernel/299788 David Teigland

    GFS requires that a failed node be fenced prior to gfs being told to
    begin recovery for that node

which sounds very plausible as according to that thread DLM itself does
not make sure fencing happens before DLM recovery, thus DLM locks could
be granted to others before the failed node is fenced (if at all).

Now more than ten years passed and I wonder

1. if the above is still true (or maybe my interpretation was wrong to
   start with)

2. how it is arranged for in the GFS2 code (I failed to find it with
   naive search phrases)

3. whether clvmd does the same

4. what are the pros/cons of disabling DLM fencing (even the dlm_stonith
   proxy) and leaving fencing fully to the resource manager (Pacemaker)

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