6.5. Disaster recovery alerts

Recording rules

• Record: ramen_sync_duration_seconds

  Expression

  sum by (obj_name, obj_namespace, obj_type, job, policyname)(time() - (ramen_last_sync_timestamp_seconds > 0))

  Purpose

  The time interval between the volume group’s last sync time and the time now in seconds.

• Record: ramen_rpo_difference

  Expression

  ramen_sync_duration_seconds{job="ramen-hub-operator-metrics-service"} / on(policyname, job) group_left() (ramen_policy_schedule_interval_seconds{job="ramen-hub-operator-metrics-service"})

  Purpose

  The difference between the expected sync delay and the actual sync delay taken by the volume replication group.

• Record: count_persistentvolumeclaim_total

  Expression

  count(kube_persistentvolumeclaim_info)

  Purpose

  Sum of all PVC from the managed cluster.

Alerts

• Alert: VolumeSynchronizationDelay

  Impact

  Critical

  Purpose

  Actual sync delay taken by the volume replication group is thrice the expected sync delay.

  YAML

    alert: VolumeSynchronizationDela
    expr: ramen_rpo_difference >= 3
    for: 5s
    labels:
      cluster: '{{ $labels.cluster }}'
      severity: critical
    annotations:
      description: >-
        Syncing of volumes (DRPC: {{ $labels.obj_name }}, Namespace: {{
        $labels.obj_namespace }}) is taking more than thrice the scheduled
        snapshot interval. This may cause data loss and a backlog of replication
        requests.
      alert_type: DisasterRecovery

• Alert: VolumeSynchronizationDelay

  Impact

  Warning

  Purpose

  Actual sync delay taken by the volume replication group is twice the expected sync delay.

  YAML

    alert: VolumeSynchronizationDela
    expr: ramen_rpo_difference > 2 and ramen_rpo_difference < 3
    for: 5s
    labels:
      cluster: '{{ $labels.cluster }}'
      severity: critical
    annotations:
      description: >-
        Syncing of volumes (DRPC: {{ $labels.obj_name }}, Namespace: {{
        $labels.obj_namespace }}) is taking more than twice the scheduled
        snapshot interval. This may cause data loss and a backlog of replication
        requests.
      alert_type: DisasterRecovery