After the follwing change was applied to the user-workload-monitoring-config ConfigMap by a ROSA customer (where the original size of the volume was 300Gi and the original storageClassName was "rosa-efs-storage"):

apiVersion: v1
data:
  config.yaml: |
    prometheus:
      retention: "15d"
      volumeClaimTemplate:
        spec:
          storageClassName: "rosa-efs-storage"
          resources:
            requests:
              storage: "20Gi"
kind: ConfigMap
metadata:
  name: user-workload-monitoring-config
  namespace: openshift-user-workload-monitoring

The prometheus pods were stuck in Init state because they were unable to mount the db volumes. Manual intervention was required to bring the Prometheus pods back (deleting old PVCs with 300Gi and deleting the prometheus pods to speed up PVC temination).

Please note that rosa-efs-storage PVCs can't be resized by changing the spec.resources.requests.storage parameter.

4.12.34

1.Create a ROSA cluster
2.edit the volume spec as described above

UWM Prometheus down

UWM Prometheus PVCs and pods are recreated automatically by the operator.