The `PDB(PodDisruptionBudget)` with `minAvailable=0` is preventing node drain when ready pod is in crashloop,error or in notready state.

4.12

   yes 

    1. Create deployment which should fail
~~~
mdeore@mdeore-mac Manifest % cat deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: test-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: test
  template:
    metadata:
      labels:
        app: test
    spec:
      containers:
      - name: nginx
        image: registry.access.redhat.com/ubi8/nginx-120
        ports:
        - containerPort: 8080
        readinessProbe:
          httpGet:
            path: /
            port: 80
          initialDelaySeconds: 10
          periodSeconds: 5
          failureThreshold: 3
~~~

    2. Create PDB with minAvailable: 0
~~~
mdeore@mdeore-mac Manifest % cat pdb.yaml
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: test-pdb1
spec:
  minAvailable: 0
  selector:
    matchLabels:
      deployment: httpd
~~~    
   3. Check pod and PDB
~~~
NAME                              READY   STATUS             RESTARTS     AGE
test-deployment-f7d699487-25bcd   0/1     CrashLoopBackOff   7 (9s ago)   11m
mdeore@mdeore-mac Manifest % oc get pdb
NAME       MIN AVAILABLE   MAX UNAVAILABLE   ALLOWED DISRUPTIONS   AGE
test-pdb   0               N/A               0                     5s
~~~
   4. Drain the node in which pod is schudled
~~~
% oc adm drain worker-1.mdeore11.lab.psi.pnq2.redhat.com --delete-local-data --ignore-daemonsets --force
~~~     

    Drain is failing due to pdb
~~~
error when evicting pods/"mypod" -n "test" (will retry after 5s): Cannot evict pod as it would violate the pod's disruption budget.
~~~

Drain should be successfull wethoud any issue for this test pod as minAvailable is set to`0`

If we do same test with pod which is in ready state. Drain is working fine wethout any issue.