[Pacemaker] [PATCH]Bug 2567 - crm resource migrate should support an optional "role" parameter

[Holger Teutsch]

Hi Dejan,

On Fri, 2011-03-18 at 14:24 +0100, Dejan Muhamedagic wrote:
> Hi,
> 
> On Fri, Mar 18, 2011 at 12:21:40PM +0100, Holger Teutsch wrote:
> > Hi,
> > I would like to submit 2 patches of an initial implementation for
> > discussion.
..
> > To recall:
> > 
> > crm_resource --move resource
> > creates a "standby" rule that moves the resource off the currently
> > active node
> > 
> > while
> > 
> > crm_resource --move resource --node newnode
> > creates a "prefer" rule that moves the resource to the new node.
> > 
> > When dealing with clones and masters the behavior was random as the code
> > only considers the node where the first instance of the clone was
> > started.
> > 
> > The new code behaves consistently for the master role of an m/s
> > resource. The options "--master" and "rsc:master" are somewhat redundant
> > as a "slave" move is not supported. Currently it's more an
> > acknowledgement of the user.
> > 
> > On the other hand it is desirable (and was requested several times on
> > the ML) to stop a single resource instance of a clone or master on a
> > specific node.
> > 
> > Should that be implemented by something like
> >  
> > "crm_resource --move-off --resource myresource --node devel2" ?
> > 
> > or should
> > 
> > crm_resource refuse to work on clones
> > 
> > and/or should moving the master role be the default for m/s resources
> > and the "--master" option discarded ?
> 
> I think that we also need to consider the case when clone-max is
> less than the number of nodes. If I understood correctly what you
> were saying. So, all of move slave and move master and move clone
> should be possible.
> 

I think the following use cases cover what can be done with such kind of
interface:

crm_resource --moveoff --resource myresource --node mynode
   -> all resource variants: check whether active on mynode, then create standby constraint

crm_resource --move --resource myresource
   -> primitive/group: convert to --moveoff --node `current_node`
   -> clone/master: refused

crm_resource --move --resource myresource --node mynode
  -> primitive/group: create prefer constraint
  -> clone/master: refused

crm_resource --move --resource myresource --master --node mynode
  -> master: create prefer constraint for master role
  -> others: refused

They should work (witch foreseeable outcome!) regardless of the setting of clone-max.

Regards
Holger


> Cheers,
> 
> Dejan
> 
> > Regards
> > Holger
>