[ClusterLabs] Resource balancing and "ptest scores"

[Ulrich Windl]

Hi!

Using a utilization-based placement strategy (placement-strategy=balanced), I wonder why pacemaker chose node h16 to place a new resource.

The situation before placement looks like this:
Remaining: h16 capacity: utl_ram=207124 utl_cpu=340
Remaining: h18 capacity: utl_ram=209172 utl_cpu=360
Remaining: h19 capacity: utl_ram=180500 utl_cpu=360

So h18 has most resources left.

A new resource prm_xen_v16 (utilization utl_cpu=40 utl_ram=16384) will be placed to h16, however, and I don't understand why:

Transition Summary:
 * Start      prm_xen_v16           ( h16 )
 * Start      prm_cron_snap_v16     ( h16 )

(the "snap" resource depends on the xen resource)

The cluster actually placed the resource as indicated, leaving:
Remaining: h16 capacity: utl_ram=190740 utl_cpu=300
Remaining: h18 capacity: utl_ram=209172 utl_cpu=360
Remaining: h19 capacity: utl_ram=180500 utl_cpu=360

So h18 still has most capacity left.

I have 5 VMs on h16, 3 VMs on h18, and 2 VMs on h19...

pacemaker-2.0.4+20200616.2deceaa3a-3.3.1.x86_64 of SLES15 SP2.

Regards,
Ulrich