Description of problem:
When create migplan for an application with PV in AWS OCP3.9 cluster, the MigAnalytic fails to get the source cluster resources, all reported as 0 sometimes.  The probability of occurrence is very high.

Version-Release number of selected component (if applicable):
MTC 1.5.0
image: quay-enterprise-quay-enterprise.apps.cam-tgt-21420.qe.devcluster.openshift.com/admin/openshift-migration-rhel7-operator:v1.5.0-23
Source cluster : AWS OCP 3.9 (controller)
Target cluster: AWS OCP 4.8

How reproducible:
1.  Prepare an nginx application in 3.9 source cluster
$ ansible-playbook deploy-app.yml -e use_role=ocp-nginxpv -e namespace=ocp-24706-basicvolmig

2. Create indirect migration plan against nginx 

3. Check analytics message in migration plan 

Actual results:
The migplan will be ready status, but there is warning message “ Failed gathering extended PV usage information for PVs [nginx-logs nginx-html] in migplan. The MigAnalytic reported as 0 

Expected results:
The migplan will be ready status without warning and error message.  The MigAnalytic reported as 0 

Additional info:
$ oc get pvc -n ocp-24706-basicvolmig
NAME     	STATUS	VOLUME                                 	CAPACITY   ACCESS MODES   STORAGECLASS   AGE
nginx-html   Bound 	pvc-602321ba-e51c-11eb-b736-0e2f00abf38f   1Gi    	RWO        	gp2        	1h
nginx-logs   Bound 	pvc-601ee567-e51c-11eb-b736-0e2f00abf38f   1Gi    	RWO        	gp2        	1h

$ oc get migplan ocp-24706-basicvolmig-migplan-1626319591  -o yaml
apiVersion: migration.openshift.io/v1alpha1
kind: MigPlan
metadata:
  ……...
  name: ocp-24706-basicvolmig-migplan-1626319591
  namespace: openshift-migration
spec:
  destMigClusterRef:
	name: target-cluster
	namespace: openshift-migration
  indirectImageMigration: true
  indirectVolumeMigration: true
  migStorageRef:
	name: automatic
	namespace: openshift-migration
  namespaces:
  - ocp-24706-basicvolmig
  persistentVolumes:
  - capacity: 1Gi
	name: pvc-601ee567-e51c-11eb-b736-0e2f00abf38f
	proposedCapacity: "0"
	pvc:
  	accessModes:
  	- ReadWriteOnce
  	hasReference: true
  	name: nginx-logs
  	namespace: ocp-24706-basicvolmig
	selection:
  	action: copy
  	copyMethod: filesystem
  	storageClass: gp2
	storageClass: gp2
	supported:
  	actions:
  	- copy
  	- move
  	copyMethods:
  	- filesystem
  	- snapshot
  - capacity: 1Gi
	name: pvc-602321ba-e51c-11eb-b736-0e2f00abf38f
	proposedCapacity: "0"
	pvc:
  	accessModes:
  	- ReadWriteOnce
  	hasReference: true
  	name: nginx-html
  	namespace: ocp-24706-basicvolmig
	selection:
  	action: copy
  	copyMethod: filesystem
  	storageClass: gp2
	storageClass: gp2
	supported:
  	actions:
  	- copy
  	- move
  	copyMethods:
  	- filesystem
  	- snapshot
  srcMigClusterRef:
	name: host
	namespace: openshift-migration
status:
  conditions:
  - category: Required
	lastTransitionTime: 2021-07-15T03:26:36Z
	message: The `persistentVolumes` list has been updated with discovered PVs.
	reason: Done
	status: "True"
	type: PvsDiscovered
  - category: Required
	lastTransitionTime: 2021-07-15T03:26:36Z
	message: The storage resources have been created.
	reason: Done
	status: "True"
	type: StorageEnsured
  - category: Warn
	lastTransitionTime: 2021-07-15T04:11:44Z
	message: Failed gathering extended PV usage information for PVs [nginx-logs nginx-html],
  	please see MigAnalytic openshift-migration/ocp-24706-basicvolmig-migplan-1626319591-szwd6
  	for details
	reason: FailedRunningDf
	status: "True"
	type: ExtendedPVAnalysisFailed
  - category: Required
	lastTransitionTime: 2021-07-15T03:26:36Z
	message: The migration plan is ready.
	status: "True"
	type: Ready
  destStorageClasses:
  - accessModes:
	- ReadWriteOnce
	default: true
	name: gp2
	provisioner: kubernetes.io/aws-ebs
  - accessModes:
	- ReadWriteOnce
	name: gp2-csi
	provisioner: ebs.csi.aws.com
  excludedResources:
………

$ oc get miganalytic ocp-24706-basicvolmig-migplan-1626319591-szwd6  -n openshift-migration -o yaml
apiVersion: migration.openshift.io/v1alpha1
kind: MigAnalytic
metadata:
 ……...
  name: ocp-24706-basicvolmig-migplan-1626319591-szwd6
  namespace: openshift-migration
spec:
  analyzeExtendedPVCapacity: true
  analyzeImageCount: false
  analyzeK8SResources: false
  analyzePVCapacity: false
  migPlanRef:
	name: ocp-24706-basicvolmig-migplan-1626319591
	namespace: openshift-migration
status:
  analytics:
	excludedk8sResourceTotal: 0
	imageCount: 0
	imageSizeTotal: "0"
	incompatiblek8sResourceTotal: 0
	k8sResourceTotal: 0
	namespaces:
	- excludedK8SResourceTotal: 0
  	imageCount: 0
  	imageSizeTotal: "0"
  	incompatibleK8SResourceTotal: 0
  	k8sResourceTotal: 0
  	namespace: ocp-24706-basicvolmig
  	persistentVolumes:
  	- actualCapacity: "0"
    	comment: No change in PV capacity is needed.
    	name: nginx-logs
    	proposedCapacity: "0"
    	requestedCapacity: 1Gi
  	- actualCapacity: "0"
    	comment: No change in PV capacity is needed.
    	name: nginx-html
    	proposedCapacity: "0"
    	requestedCapacity: 1Gi
  	pvCapacity: "0"
  	pvCount: 0
	percentComplete: 100
	plan: ocp-24706-basicvolmig-migplan-1626319591
	pvCapacity: "0"
	pvCount: 0
  conditions:
  - category: Warn
	lastTransitionTime: 2021-07-15T03:26:34Z
	message: Failed gathering extended PV usage information for PVs [nginx-logs nginx-html]
	reason: FailedRunningDf
	status: "True"
	type: ExtendedPVAnalysisFailed
  - category: Required
	lastTransitionTime: 2021-07-15T03:26:34Z
	message: The analytic is ready.
	status: "True"
	type: Ready
  observedGeneration: 1