[Pacemaker] Build dlm_controld for pacemaker stack (dlm_controld.pcmk)

Andrew Beekhof andrew at beekhof.net
Thu Nov 1 19:05:14 EDT 2012

On Thu, Nov 1, 2012 at 5:09 PM, Vladislav Bogdanov <bubble at hoster-ok.com> wrote:
> 01.11.2012 02:47, Andrew Beekhof wrote:
> ...
>>> One remark about that - it requires that gfs2 communicates with dlm in
>>> the kernel space - so gfs_controld is not longer required. I think
>>> Fedora 17 is the first version with that feature. And it is definitely
>>> not available for EL6 (centos6 which I use).
>>> But I have preliminary success running GFS2 with corosync2 and pacemaker
>>> 1.1.8 on EL6. dlm4 runs just fine as is (although it misses some
>>> featured on EL6 because of kernel). And it still includes (not
>>> documented) option enable_fscontrol, so user-space communication with fs
>>> control daemons is supported. Even it that feature will be removed
>>> upstream, it can be easily returned back - just several lines of code.
>>> And I ported gfs_controld from cman to corosync2 (patch is very dirty
>>> yet, made with scissors and needle, just a proof-of-concept that it even
>>> can work). Some features are unsupported (f.e. nodir) and will not be
>>> implemented by me.
>> I'm impressed.  What was the motivation though?  You really really
>> don't like CMAN? :-)
> Why should I like software which is going to die? ;)
> I believe that how things are done currently (third case from your list)
> fully reflect my "perfectionistic" needs. I had many problems with
> cman+pacemaker in a past. Most critical is that pacemaker and
> dlm_controld react differently when node reappears back very soon after
> if was lost (because pacemaker uses totem ? directly for membership, but
> dlm uses CPG).

We both get it from the CPG and quorum APIs for option 3.

> Pacemaker accepts that, but controld freezes lockspaces,
> waiting for fencing. But fencing is never done because nobody handles
> "node lost" CPG event.

WTF.  Pacemaker should absolutely do this.  Bug report?

> dlm does start fencing for "process lost", but
> not for "node lost".
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