[ClusterLabs] Coming in Pacemaker 1.1.17: start a node in standby

[Lars Ellenberg]

On Tue, Apr 25, 2017 at 10:27:43AM +0200, Jehan-Guillaume de Rorthais wrote:
> On Tue, 25 Apr 2017 10:02:21 +0200
> Lars Ellenberg <lars.ellenberg at linbit.com> wrote:
> 
> > On Mon, Apr 24, 2017 at 03:08:55PM -0500, Ken Gaillot wrote:
> > > Hi all,
> > > 
> > > Pacemaker 1.1.17 will have a feature that people have occasionally asked
> > > for in the past: the ability to start a node in standby mode.  
> > 
> > 
> > I seem to remember that at some deployment,
> > we set the node instance attribute standby=on, always,
> > and took it out of standby using the node_state transient_attribute :-)
> > 
> > As in
> > # crm node standby ava
> >   <node id="1" uname="ava">
> >     <instance_attributes id="nodes-1">
> >       <nvpair id="nodes-1-standby" name="standby" value="on"/>
> >       ...
> >     </instance_attributes>
> >   </node>
> >   ...
> 
> This solution seems much more elegant and obvious to me. A cli
> (crm_standby?) interface would be ideal.
> 
> It feels weird to mix setup interfaces (through crm_standby or through the
> config file) to manipulate the same node attribute. Isn't it possible to set
> the standby instance attribute of a node **before** it is added to the cluster?
> 
> > # crm node status-attr ava set standby off
> >   <node_state id="1" uname="ava" in_ccm="true" crmd="online"
> > crm-debug-origin="do_update_resource" join="member" expected="member"> ...
> >     <transient_attributes id="1">
> >       <instance_attributes id="status-1">
> > 	...
> >         <nvpair id="status-1-standby" name="standby" value="off"/>
> >       </instance_attributes>
> >     </transient_attributes>
> >   </node_state>
> 
> It is not really straight forward to understand why you need to edit a second
> different nvpair to exit the standby mode... :/

Well, you want the "persistent" setting "on",
and override it with a "transient" setting "off".

That's how to do it in pacemaker.

But yes, what exactly has ever been "obvious" in pacemaker,
before you knew?  :-)        (or HA in general, to be fair)

-- 
: Lars Ellenberg
: LINBIT | Keeping the Digital World Running
: DRBD -- Heartbeat -- Corosync -- Pacemaker
: R&D, Integration, Ops, Consulting, Support

DRBD® and LINBIT® are registered trademarks of LINBIT