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OSDOCS#12034: HCP Kubevirt topology spread constraint

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xenolinux
2025-03-11 15:22:36 +05:30
committed by openshift-cherrypick-robot
parent f516df7dd8
commit e984ba0972
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hosted_control_planes/hcp-manage/hcp-manage-virt.adoc
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include::modules/hcp-virt-attach-nvidia-gpus.adoc[leveloffset=+1]
include::modules/hcp-virt-attach-nvidia-gpus-np-api.adoc[leveloffset=+1]
include::modules/hcp-topology-spread-constraint.adoc[leveloffset=+1]
[role="_additional-resources"]
.Additional resources
* xref:../../nodes/scheduling/descheduler/nodes-descheduler-configuring.adoc#nodes-descheduler-installing_virt-enabling-descheduler-evictions[Installing the descheduler]

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modules/hcp-topology-spread-constraint.adoc Normal file
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// Module included in the following assemblies:
//
// * hosted_control_planes/hcp-manage/hcp-manage-virt.adoc
:_mod-docs-content-type: PROCEDURE
[id="hcp-topology-spread-constraint_{context}"]
= Spreading node pool VMs by using topologySpreadConstraint
By default, KubeVirt virtual machines (VMs) created by a node pool are scheduled on any available nodes that have the capacity to run the VMs. By default, the `topologySpreadConstraint` constraint is set to schedule VMs on multiple nodes.
In some scenarios, node pool VMs might run on the same node, which can cause availability issues. To avoid distribution of VMs on a single node, use the descheduler to continuously honor the `topologySpreadConstraint` constraint to spread VMs on multiple nodes.
.Prerequisites
* You installed the {descheduler-operator}. For more information, see "Installing the descheduler".
.Procedure
* Open the `KubeDescheduler` custom resource (CR) by entering the following command, and then modify the `KubeDescheduler` CR to use the `SoftTopologyAndDuplicates` and `DevKubeVirtRelieveAndMigrate` profiles so that you maintain the `topologySpreadConstraint` constraint settings.
+
The `KubeDescheduler` CR named `cluster` runs in the `openshift-kube-descheduler-operator` namespace.
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[source,terminal]
----
$ oc edit kubedescheduler cluster -n openshift-kube-descheduler-operator
----
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.Example `KubeDescheduler` configuration
[source,yaml]
----
apiVersion: operator.openshift.io/v1
kind: KubeDescheduler
metadata:
name: cluster
namespace: openshift-kube-descheduler-operator
spec:
mode: Automatic
managementState: Managed
deschedulingIntervalSeconds: 30 # <1>
profiles:
- SoftTopologyAndDuplicates # <2>
- DevKubeVirtRelieveAndMigrate # <3>
profileCustomizations:
devDeviationThresholds: AsymmetricLow
devActualUtilizationProfile: PrometheusCPUCombined
# ...
----
<1> Sets the number of seconds between the descheduler running cycles.
<2> This profile evicts pods that follow the soft topology constraint: `whenUnsatisfiable: ScheduleAnyway`.
<3> This profile balances resource usage between nodes and enables the strategies, such as `RemovePodsHavingTooManyRestarts` and `LowNodeUtilization`.