Empty schedule is not supported in the Backup CR. 

    Always

    1. Apply the below CR

apiVersion: config.openshift.io/v1alpha1
kind: Backup
metadata:
  name: default
spec:
  etcd:
    schedule: ""
    timeZone: "UTC"
    retentionPolicy:
      retentionType: RetentionNumber
      retentionNumber:
        maxNumberOfBackups: 2


Fails with error:
The Backup "default" is invalid: spec.etcd.schedule: Invalid value: "": spec.etcd.schedule in body should match '^(@(annually|yearly|monthly|weekly|daily|hourly))|(\*|(?:\*|(?:[0-9]|(?:[1-5][0-9])))\/(?:[0-9]|(?:[1-5][0-9]))|(?:[0-9]|(?:[1-5][0-9]))(?:(?:\-[0-9]|\-



    2. When schedule itself is not mentioned.
The backup pod failed with error:

$ oc logs backup-server-daemon-set-m96bv
F1022 13:26:10.239742       1 backupserver.go:77] error parsing backup schedule : empty spec string


    
    

    empty schedule should be supported.