BZ1978420: Add a PodDisruptionBudget related bullet in prerequisites

Author: xenolinux

updating/updating-cluster-cli.adoc

@@ -25,6 +25,7 @@ See xref:../authentication/using-rbac.adoc[Using RBAC to define and apply permis
 * If your cluster uses manually maintained credentials with the AWS Secure Token Service (STS), obtain a copy of the `ccoctl` utility from the release image being updated to and use it to process any updated credentials. For more information, see xref:../authentication/managing_cloud_provider_credentials/cco-mode-sts.adoc#sts-mode-upgrading[Upgrading an OpenShift Container Platform cluster configured for manual mode with STS].
 * Ensure that you address all `Upgradeable=False` conditions so the cluster allows an update to the next minor version. An alert displays at the top of the *Cluster Settings* page when you have one or more cluster Operators that cannot be upgraded. You can still update to the next available patch update for the minor release you are currently on.
 * Review the list of APIs that were removed in Kubernetes 1.25, migrate any affected components to use the new API version, and provide the administrator acknowledgment. For more information, see xref:../updating/updating-cluster-prepare.adoc#updating-cluster-prepare[Preparing to update to {product-title} 4.12].
+* If you run an Operator or you have configured any application with the pod disruption budget, you might experience an interruption during the upgrade process. If `minAvailable` is set to 1 in `PodDisruptionBudget`, the nodes are drained to apply pending machine configs which might block the eviction process. If several nodes are rebooted, all the pods might run on only one node, and the `PodDisruptionBudget` field can prevent the node drain.
 
 [IMPORTANT]
 ====

updating/updating-cluster-rhel-compute.adoc

@@ -18,6 +18,7 @@ See xref:../authentication/using-rbac.adoc[Using RBAC to define and apply permis
 * Support for {op-system-base}7 workers is removed in {product-title} {product-version}. You must replace {op-system-base}7 workers with {op-system-base}8 or {op-system} workers before upgrading to {product-title} {product-version}. Red Hat does not support in-place {op-system-base}7 to {op-system-base}8 upgrades for {op-system-base} workers; those hosts must be replaced with a clean operating system install.
 * If your cluster uses manually maintained credentials, ensure that the Cloud Credential Operator (CCO) is in an upgradeable state. For more information, see _Upgrading clusters with manually maintained credentials_ for xref:../installing/installing_aws/manually-creating-iam.adoc#manually-maintained-credentials-upgrade_manually-creating-iam-aws[AWS], xref:../installing/installing_azure/manually-creating-iam-azure.adoc#manually-maintained-credentials-upgrade_manually-creating-iam-azure[Azure], or xref:../installing/installing_gcp/manually-creating-iam-gcp.adoc#manually-maintained-credentials-upgrade_manually-creating-iam-gcp[GCP].
 * If your cluster uses manually maintained credentials with the AWS Secure Token Service (STS), obtain a copy of the `ccoctl` utility from the release image being updated to and use it to process any updated credentials. For more information, see xref:../authentication/managing_cloud_provider_credentials/cco-mode-sts.adoc#sts-mode-upgrading[_Upgrading an OpenShift Container Platform cluster configured for manual mode with STS_].
+* If you run an Operator or you have configured any application with the pod disruption budget, you might experience an interruption during the upgrade process. If `minAvailable` is set to 1 in `PodDisruptionBudget`, the nodes are drained to apply pending machine configs which might block the eviction process. If several nodes are rebooted, all the pods might run on only one node, and the `PodDisruptionBudget` field can prevent the node drain.
 
 [role="_additional-resources"]
 .Additional resources

updating/updating-cluster-within-minor.adoc

@@ -26,6 +26,7 @@ See xref:../authentication/using-rbac.adoc[Using RBAC to define and apply permis
 * If your cluster uses manually maintained credentials, ensure that the Cloud Credential Operator (CCO) is in an upgradeable state. For more information, see xref:../updating/updating-cluster-cli.adoc#manually-maintained-credentials-upgrade_updating-cluster-cli[Upgrading clusters with manually maintained credentials].
 * If your cluster uses manually maintained credentials with the AWS Secure Token Service (STS), obtain a copy of the `ccoctl` utility from the release image being updated to and use it to process any updated credentials. For more information, see xref:../authentication/managing_cloud_provider_credentials/cco-mode-sts.adoc#sts-mode-upgrading[Upgrading an OpenShift Container Platform cluster configured for manual mode with STS].
 * Review the list of APIs that were removed in Kubernetes 1.25, migrate any affected components to use the new API version, and provide the administrator acknowledgment. For more information, see xref:../updating/updating-cluster-prepare.adoc#updating-cluster-prepare[Preparing to update to {product-title} 4.12].
+* If you run an Operator or you have configured any application with the pod disruption budget, you might experience an interruption during the upgrade process. If `minAvailable` is set to 1 in `PodDisruptionBudget`, the nodes are drained to apply pending machine configs which might block the eviction process. If several nodes are rebooted, all the pods might run on only one node, and the `PodDisruptionBudget` field can prevent the node drain.
 
 [IMPORTANT]
 ====

updating/updating-restricted-network-cluster.adoc

@@ -26,6 +26,7 @@ See xref:../authentication/using-rbac.adoc[Using RBAC to define and apply permis
 * If your cluster uses manually maintained credentials, ensure that the Cloud Credential Operator (CCO) is in an upgradeable state. For more information, see _Upgrading clusters with manually maintained credentials_ for xref:../installing/installing_aws/manually-creating-iam.adoc#manually-maintained-credentials-upgrade_manually-creating-iam-aws[AWS], xref:../installing/installing_azure/manually-creating-iam-azure.adoc#manually-maintained-credentials-upgrade_manually-creating-iam-azure[Azure], or xref:../installing/installing_gcp/manually-creating-iam-gcp.adoc#manually-maintained-credentials-upgrade_manually-creating-iam-gcp[GCP].
 //STS is not currently supported in a restricted network environment, but the following bullet can be uncommented when that changes.
 //* If your cluster uses manually maintained credentials with the AWS Secure Token Service (STS), obtain a copy of the `ccoctl` utility from the release image being upgraded to and use it to process any updated credentials. For more information, see xref:../authentication/managing_cloud_provider_credentials/cco-mode-sts.adoc#sts-mode-upgrading[_Upgrading an OpenShift Container Platform cluster configured for manual mode with STS_].
+* If you run an Operator or you have configured any application with the pod disruption budget, you might experience an interruption during the upgrade process. If `minAvailable` is set to 1 in `PodDisruptionBudget`, the nodes are drained to apply pending machine configs which might block the eviction process. If several nodes are rebooted, all the pods might run on only one node, and the `PodDisruptionBudget` field can prevent the node drain.
 
 [id="updating-restricted-network-mirror-host"]
 === Preparing your mirror host