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openshift-docs/modules/virt-runbook-lowvirtcontrollerscount.adoc
2023-10-30 10:13:25 -04:00

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// Do not edit this module. It is generated with a script.
// Do not reuse this module. The anchor IDs do not contain a context statement.
// Module included in the following assemblies:
//
// * virt/monitoring/virt-runbooks.adoc
:_mod-docs-content-type: REFERENCE
[id="virt-runbook-LowVirtControllersCount"]
= LowVirtControllersCount
[discrete]
[id="meaning-lowvirtcontrollerscount"]
== Meaning
This alert fires when a low number of `virt-controller` pods is detected. At
least one `virt-controller` pod must be available in order to ensure high
availability. The default number of replicas is 2.
A `virt-controller` device monitors the custom resource definitions (CRDs) of a
virtual machine instance (VMI) and manages the associated pods. The device
create pods for VMIs and manages the lifecycle of the pods. The device is
critical for cluster-wide virtualization functionality.
[discrete]
[id="impact-lowvirtcontrollerscount"]
== Impact
The responsiveness of {VirtProductName} might become negatively
affected. For example, certain requests might be missed.
In addition, if another `virt-launcher` instance terminates unexpectedly,
{VirtProductName} might become completely unresponsive.
[discrete]
[id="diagnosis-lowvirtcontrollerscount"]
== Diagnosis
. Set the `NAMESPACE` environment variable:
+
[source,terminal]
----
$ export NAMESPACE="$(oc get kubevirt -A \
-o custom-columns="":.metadata.namespace)"
----
. Verify that running `virt-controller` pods are available:
+
[source,terminal]
----
$ oc -n $NAMESPACE get pods -l kubevirt.io=virt-controller
----
. Check the `virt-launcher` logs for error messages:
+
[source,terminal]
----
$ oc -n $NAMESPACE logs <virt-launcher>
----
. Obtain the details of the `virt-launcher` pod to check for status conditions
such as unexpected termination or a `NotReady` state.
+
[source,terminal]
----
$ oc -n $NAMESPACE describe pod/<virt-launcher>
----
[discrete]
[id="mitigation-lowvirtcontrollerscount"]
== Mitigation
This alert can have a variety of causes, including:
* Not enough memory on the cluster
* Nodes are down
* The API server is overloaded. For example, the scheduler might be under a
heavy load and therefore not completely available.
* Networking issues
Identify the root cause and fix it, if possible.
If you cannot resolve the issue, log in to the
link:https://access.redhat.com[Customer Portal] and open a support case,
attaching the artifacts gathered during the diagnosis procedure.