CTDB and Recovery lock

[Martin Schwenke]

Hi Partha,

On Wed, 18 Nov 2015 13:05:51 -0800, Partha Sarathi
<parthasarathi.bl at gmail.com> wrote:

> Thanks Martin for a brief note on it. The cluster wide mutex make more
> sense now.  I noticed this is been used in Zookeeper too
> 
> https://issues.apache.org/jira/browse/CASSANDRA-704
 
> On Wed, Nov 18, 2015 at 12:18 AM, Martin Schwenke <martin at meltin.net> wrote:

> > On Tue, 17 Nov 2015 14:00:11 -0800, Partha Sarathi
> > <parthasarathi.bl at gmail.com> wrote:
> >  
>  [...]  
> >  
>  [...]  
> >  
> > > Thanks a lot Martin for your detailed answers.
> > >
> > > Now I am more interested about the "configurable helper program" you
> > > mentioned  which replaces the recovery lock mechanism. May I know little
> > > more about it ?.  
> >
> > We are thinking of an executable similar to the current
> > ctdb_event_helper.   [...]
> >
> > The behaviour would be something like this:
> >
> > * If the cluster-wide mutex can be taken then write 0 to the status file
> >   descriptor and hold the mutex until terminated with a signal or the
> >   parent exits.
> > [...]

This didn't make it into Samba 4.4 but is now in Samba master, so it
will be in Samba 4.5.

Documentation for writing helpers is at:

  https://git.samba.org/?p=samba.git;a=blob;f=ctdb/doc/cluster_mutex_helper.txt

peace & happiness,
martin