Hello,
I have a question regarding preferred anti-affinity pod placement rules.
I have the following situation: OpenShift 3.11 cluster with 3 masters
and 6 nodes (each 62GB and 32 cores [node-932 with 86GB/44cores]) with
spare capacities as follows (output from 'oc describe node'):
node-910 (62GB):
cpu 8465m (26%) 9225m (28%)
memory 14042Mi (21%) 13762Mi (21%)
node-911 (62GB):
cpu 13580m (42%) 15440m (48%)
memory 21917944928 (32%) 27898900096 (41%)
node-912 (62GB):
cpu 8210m (25%) 8220m (25%)
memory 12808Mi (19%) 12728Mi (19%)
node-913 (62GB):
cpu 4210m (13%) 4220m (13%)
memory 8712Mi (13%) 8632Mi (13%)
node-914 (62GB):
cpu 4250m (13%) 4280m (13%)
memory 10460252672 (15%) 11208594432 (16%)
node-915 (62GB):
cpu 8430m (26%) 9240m (28%)
memory 12086Mi (18%) 11806Mi (18%)
node-930 (62GB):
cpu 8310m (25%) 8220m (25%)
memory 13064Mi (20%) 12728Mi (19%)
node-932 (86GB):
cpu 210m (0%) 220m (0%)
memory 520Mi (0%) 440Mi (0%)
There's a 3-node Mongo cluster running, with pods placed as follows:
node-913:
mongo-2-5-zl7gh
node-914:
mongo-1-5-crz4l
node-915:
mongo-0-5-w7mbr
There are other pods on the nodes, but they aren't referenced in my
anti-affinity rule, so I've omitted them for simplicity.
The mongo-[012] pods' contain a service label as follows:
labels:
[..]
service: mongo
The config for our app-a deployment contains the following specs and
affinity rules:
[..]
template:
metadata:
[..]
labels:
name: app-a
service: app
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- podAffinityTerm:
labelSelector:
matchExpressions:
- key: service
operator: In
values:
- mongo
topologyKey: kubernetes.io/hostname
weight: 100
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: name
operator: In
values:
- app-a
topologyKey: kubernetes.io/hostname
containers:
[..]
resources:
limits:
cpu: '8'
memory: 12Gi
requests:
cpu: '8'
memory: 12Gi
[..]
So new app-a pods should quite comfortably fit unto any of the nodes.
It appears that the requiredDuringSchedulingIgnoredDuringExecution
anti-affinity rule is being observed as expected. Two app-a pods are
never deployed to the same node.
However the preferredDuringSchedulingIgnoredDuringExecution rule seems
to be ignored by the scheduler.
If I deploy four app-a pods in the situation above, they are deployed to
nodes 910, 913, 914 and 932, thus pairing them up with mongo pods on
nodes 913 and 914.
Is this the expected behaviour?
Thanks,
Andre
_______________________________________________
users mailing list
users@lists.openshift.redhat.com
http://lists.openshift.redhat.com/openshiftmm/listinfo/users
