[Pacemaker] Removing resource from group without disturbing remaining resources in group

[Andreas Mock]

Hi Dejan,

we need colocation and order constraints.
IMHO it's an use case for sets, but I have to admit
that I don't really understand how to configure them
with crm. A group gives a group resource id which I
can use as reference in the contraints. It makes the
config simple.


IP1-|
IP2---> service
IP3-|

IP1 .. IP40

Advices welcome.

Best regards
Andreas



-----Ursprüngliche Nachricht-----
Von: Dejan Muhamedagic [mailto:dejanmm at fastmail.fm] 
Gesendet: Freitag, 7. Juni 2013 15:55
An: 'The Pacemaker cluster resource manager'
Betreff: Re: [Pacemaker] Removing resource from group without disturbing
remaining resources in group

On Thu, Jun 06, 2013 at 06:15:26PM +0200, Andreas Mock wrote:
> Hi Florian,
> 
> thank you very much for that method description.
> It seems that it does exactly what we want. By the way.
> It's the same use case as yours. Many IP for which we
> want a constraint handle (group).

But wouldn't just a collocation constraint do if the order is not
important?

Thanks,

Dejan

> Thank you!
> 
> Best regards
> Andreas Mock
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: Florian Crouzat [mailto:gentoo at floriancrouzat.net] 
> Gesendet: Donnerstag, 6. Juni 2013 16:50
> An: pacemaker at oss.clusterlabs.org
> Betreff: Re: [Pacemaker] Removing resource from group without disturbing
> remaining resources in group
> 
> Le 06/06/2013 16:35, Andreas Mock a écrit :
> > Hi all,
> >
> > is there a way to remove a resource from a group without
> > disturbing the other resources in the group.
> >
> > The following example:
> > - G1 has R1 R2 R3
> > - All resources are started
> > - Stopping R1 would cause a stop of R2 R3
> > - So, the idea was:
> > * crm configure edit => remove R1 from the group while running
> > * stop resource
> > * delete resource
> >
> > BUT: At some point (which we couldn't find out at
> > the moment) all remaining resources of the group are
> > restarted. It seems that the change of the implicit
> > dependency tree of the initial group forces a rebuild
> > of that tree including a restart of that group.
> > (Andrew: Is this assumption right?)
> >
> > So, is there are way to add/remove resources from
> > group without disturbing the other resources.
> > It's clear to me that the resources would restart
> > when the node assignment after removing would change.
> >
> > Hints welcome.
> >
> 
> Approximative syntax, do not blame me !
> 
> * crm configure property maintenance-mode=true
> * crm resource stop R1 # it won't stop as it's in maintenance-mode
> * crm configure delete R1
> * crm configure show # very that all references to R1 are gone
> * crm resource reprobe # the cluster double check the status of declared 
> resources and sees that everything is fine and R1 doesn't exists anymore
> * crm_mon -Arf1 # double check that everything is "started (unmanaged)" 
> and R1 is gone
> * crm_simulate -S -L -VVV # optional, to check what would happen when 
> leaving maintenance-mode
> * crm configure property maintenance-mode=false
> 
> If something goes wrong while in maintenance-mode, crm resource cleanup 
> foo might be handy. Nothing should move, start or stop until you leave 
> maintenance-mode anyway. I use this scenario very often, to add or 
> remove IPaddr2 resources to a group of 30+ IPaddr2.
> 
> 
> -- 
> Cheers,
> Florian Crouzat
> 
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