[ClusterLabs] ?==?utf-8?q? Limit of concurrent ressources to start?

[Ken Gaillot]

On Wed, 2018-06-13 at 14:25 +0200, Michael Schwartzkopff wrote:
> On Wednesday, June 13, 2018 10:01 CEST, "Michael Schwartzkopff" <ms at s
> ys4.de> wrote: 
>  
> > Hi,
> > 
> > we have a cluster with several IP addresses that can start after an
> > other resource. In the logs we see that only 2 IP addresses start
> > in parallel, not all. Can anyone please explain, why not all IP
> > addresses start in parallel?
> > 
> > Config:
> > primitive resProc ocf:myprovider:Proc
> > (ten times:) primitive resIP1 ocf:heartbeat:IPaddr2 params
> > ip="192.168.100.1"
> > order ord_Proc_IP Mandatory: resProc ( resIP1 resIP2 ... )
> > collocation col_IP_Proc inf: (resIP1 resIP2 ...) resProc
> > 
> > No batch-limit in properties.
> > Any ideas? Thanks.
> > 
> > Michael

Each node has a limit of how many jobs it can execute in parallel. In
order of most preferred to least, it will be:

* The value of the (undocumented) PCMK_node_action_limit environment
variable on that node (no limit if not existing)

* The value of the (also undocumented) node-action-limit cluster
property (defaulting to 0 meaning no limit)

* Twice the node's number of CPU cores (as reported by /proc/stat)

Also, the cluster will auto-calculate a cluster-wide batch-limit if
high load is observed on any node.

So, you could mostly override throttling by setting a high node-action-
limit.

> Hi,
> 
> additional remark:
> 
> With some tweaks I made my cluster start two resources (i.e. IP1 and
> IP2) at the same time. But it takes about 4 seconds to that the
> cluster starts the next resources (i.e. IP3 and IP4).
> 
> Did anybody see this behaviour before?
> 
> Why does my cluster do not start all "parallel" resources together?
> 
> Michael.

Ken Gaillot <kgaillot at redhat.com>
-- 
Ken Gaillot <kgaillot at redhat.com>