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

[Dejan Muhamedagic]

Hi Holger,

On Tue, Apr 05, 2011 at 01:19:56PM +0200, Holger Teutsch wrote:
> Hi Dejan,
> 
> On Tue, 2011-04-05 at 12:27 +0200, Dejan Muhamedagic wrote:
> > On Tue, Apr 05, 2011 at 12:10:48PM +0200, Holger Teutsch wrote:
> > > Hi Dejan,
> > > 
> > > On Tue, 2011-04-05 at 11:48 +0200, Dejan Muhamedagic wrote:
> > > > Hi Holger,
> > > > 
> > > > On Mon, Apr 04, 2011 at 09:31:02PM +0200, Holger Teutsch wrote:
> > > > > On Mon, 2011-04-04 at 15:24 +0200, Andrew Beekhof wrote:
> > > > [...]
> > > > > 
> > > > > crm_resource --move-off --resource myClone --node C
> > > > >    -> I want the instance moved off C, regardless where it is moved on
> > > > 
> > > > What is the difference between move-off and unmigrate (-U)?
> > > 
> > > --move-off -> create a constraint that a resource should *not* run on
> > > the specific node (partly as before --move without --node)
> > > 
> > > -U: zap all migration constraints (as before) 
> > 
> > Ah, right, sorry, wanted to ask about the difference between
> > move-off and move. The description looks the same as for move. Is
> > it that in this case it is for clones so crm_resource needs an
> > extra node parameter? You wrote in the doc:
> > 
> > 	+Migrate a resource (-instance for clones/masters) off the specified node.
> > 
> > The '-instance' looks somewhat funny. Why not say "Move/migrate a
> > clone or master/slave instance away from the specified node"?
> 
> Moving away works for all kinds of resources so the text now looks like:
> 
> diff -r b4f456380f60 doc/crm_cli.txt
> --- a/doc/crm_cli.txt	Thu Mar 17 09:41:25 2011 +0100
> +++ b/doc/crm_cli.txt	Tue Apr 05 13:08:10 2011 +0200
> @@ -818,10 +818,25 @@
>  running on the current node. Additionally, you may specify a
>  lifetime for the constraint---once it expires, the location
>  constraint will no longer be active.
> +For a master resource specify <rsc>:master to move the master role.
>  
>  Usage:
>  ...............
> -        migrate <rsc> [<node>] [<lifetime>] [force]
> +        migrate <rsc>[:master] [<node>] [<lifetime>] [force]
> +...............
> +
> +[[cmdhelp_resource_migrateoff,migrate a resource off the specified
> node]]
> +==== `migrateoff` (`moveoff`)
> +
> +Migrate a resource away from the specified node. 
> +The resource is migrated by creating a constraint which prevents it
> from
> +running on the specified node. Additionally, you may specify a
> +lifetime for the constraint---once it expires, the location
> +constraint will no longer be active.
> +
> +Usage:
> +...............
> +        migrateoff <rsc> <node> [<lifetime>] [force]
>  ...............
>  
>  [[cmdhelp_resource_unmigrate,unmigrate a resource to another node]]
> 
> > 
> > I must say that I still find all this quite confusing, i.e. now
> > we have "move", "unmove", and "move-off", but it's probably just me :)
> 
> Think of "move" == "move-to" then it is simpler 8-)
> 
> ... keeping in mind that for backward compatibility
> 
> crm_resource --move --resource myResource
> 
> is equivalent
> 
> crm_resource --move-off --resource myResource --node $(current node)
> 
> But as there is no "current node" for clones / masters the old
> implementation did some random movements...

OK. Thanks for the clarification. I'd like to revise my previous
comment about restricting use of certain constructs. For
instance, in this case, if the command would result in a random
movement then the shell should at least issue a warning about it.
Or perhaps refuse to do that completely. I didn't take a look yet
at the code, perhaps you've already done that.

Thanks,

Dejan


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