[Pacemaker] staggered resource startup

[Andrew Beekhof]

On 04/09/2013, at 1:01 AM, Matthew O'Connor <matt at ecsorl.com> wrote:

> 
> On 08/27/2013 06:18 PM, Andrew Beekhof wrote:
> > Are you aware of this cluster
>       option?
> 
> 
>       >
> 
> 
>       >        batch-limit = integer [30]
> 
> 
>       >            The number of jobs that the TE is allowed to
>       execute in parallel
> 
> 
>       >
> 
> 
>       >            The "correct" value will depend on the speed and
>       load of your network and cluster nodes.
> 
> 
>       >
> 
> 
>       > As long as the VMs are truly started before the resource
>       agent reports "done", then lowering this value should spread the
>       load out more.
> 
> 
>       >
> 
> 
>       > There is also the possibility to specify ordering constraints
>       with kind=Serialize:
> 
> 
>       >
> 
> 
>       >   
> 
> http://clusterlabs.org/doc/en-US/Pacemaker/1.1-crmsh/html/Pacemaker_Explained/s-resource-ordering.html
> 
> No, I was not aware of this option.  The catch to the batch-limit will be with the resource agent, as you said.  AFAIK this particular resource agent reports that a VM is started once libvirt reports it's started, though "started" and "booted" are very different states and libvirt does not care about whether or not the VM successfully booted.  The load I'm trying to limit occurs after the VM is started, i.e. while it's booting.  So, I'm thinking to get what I want, I will need to use the batch-limit in conjunction with a modified resource agent that will delay reporting success until some timeout has been reached.  Ick...but better than nothing! :)

A case could be made that the upstream agent should, perhaps optionally, wait for the VM to be booted before reporting success as well.
If you can make the change generic enough, I'd encourage you to submit it for inclusion.

> 
> Thanks for the info!
> -- Matthew
> 
> 
> -- 
> Thank you!
>   Matthew O'Connor
>   (GPG Key ID: 55F981C4)
> 
> 
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