diff --git a/pkg/apis/v1alpha/storage/storage_handler.go b/pkg/apis/v1alpha/storage/storage_handler.go
index fd9c7170e..1964cf31b 100644
--- a/pkg/apis/v1alpha/storage/storage_handler.go
+++ b/pkg/apis/v1alpha/storage/storage_handler.go
@@ -22,7 +22,7 @@ func Register(ws *restful.WebService, subPath string) {
 }
 
 // List all PersistentVolumeClaims of a specific StorageClass
-// Extended API URL: "GET /api/v1alpha/storage/storageclasses/{name}/persistentvolumeclaims"
+// Extended API URL: "GET /api/v1alpha1/storage/storageclasses/{name}/persistentvolumeclaims"
 func GetPvcListBySc(request *restful.Request, response *restful.Response) {
 	scName := request.PathParameter("storageclass")
 	claims, err := models.GetPvcListBySc(scName)
@@ -35,7 +35,7 @@ func GetPvcListBySc(request *restful.Request, response *restful.Response) {
 }
 
 // Get metrics of a specific StorageClass
-// Extended API URL: "GET /api/v1alpha/storage/storageclasses/{name}/metrics"
+// Extended API URL: "GET /api/v1alpha1/storage/storageclasses/{name}/metrics"
 func GetScMetrics(request *restful.Request, response *restful.Response) {
 	scName := request.PathParameter("storageclass")
 	metrics, err := models.GetScMetrics(scName)
diff --git a/pkg/apis/v1alpha/volumes/volumes_handler.go b/pkg/apis/v1alpha/volumes/volumes_handler.go
index 57ba71495..4115f96e7 100644
--- a/pkg/apis/v1alpha/volumes/volumes_handler.go
+++ b/pkg/apis/v1alpha/volumes/volumes_handler.go
@@ -17,7 +17,7 @@ func Register(ws *restful.WebService, subPath string) {
 }
 
 // List all pods of a specific PVC
-// Extended API URL: "GET /api/v1alpha/volumes/namespaces/{namespace}/persistentvolumeclaims/{name}/pods"
+// Extended API URL: "GET /api/v1alpha1/volumes/namespaces/{namespace}/persistentvolumeclaims/{name}/pods"
 func GetPodListByPvc(request *restful.Request, response *restful.Response) {
 	pvcName := request.PathParameter("pvc")
 	nsName := request.PathParameter("namespace")
diff --git a/pkg/models/storage.go b/pkg/models/storage.go
index 53a7a6a90..4980d1629 100644
--- a/pkg/models/storage.go
+++ b/pkg/models/storage.go
@@ -23,31 +23,40 @@ type StorageMetrics struct {
 	Usage    string `json:"usage,omitempty"`
 }
 
+// List persistent volume claims of a specific storage class
 func GetPvcListBySc(storageclass string) (res []v12.PersistentVolumeClaim, err error) {
-
+	// Create Kubernetes client
 	cli := client.NewK8sClient()
+	// Get all persistent volume claims
 	claimList, err := cli.CoreV1().PersistentVolumeClaims("").List(v1.ListOptions{})
 	if err != nil {
 		return nil, err
 	}
-
+	// Select persistent volume claims which
+	// storage class name is equal to the specific storage class.
 	for _, claim := range claimList.Items {
-		if *claim.Spec.StorageClassName != storageclass {
+		if claim.Spec.StorageClassName != nil &&
+			*claim.Spec.StorageClassName == storageclass {
+			res = append(res, claim)
+		} else {
 			continue
 		}
-		res = append(res, claim)
 	}
 	return res, nil
 }
 
+// Get metrics of a specific storage class
 func GetScMetrics(storageclass string) (res StorageMetrics, err error) {
+	// Create Kubernetes client
 	cli := client.NewK8sClient()
+	// Get persistent volumes
 	pvList, err := cli.CoreV1().PersistentVolumes().List(v1.ListOptions{})
 	if err != nil {
 		return StorageMetrics{}, err
 	}
 
 	var total resource.Quantity
+	// Gathering metrics of a specific storage class
 	for _, volume := range pvList.Items {
 		if volume.Spec.StorageClassName != storageclass {
 			continue
diff --git a/pkg/models/volumes.go b/pkg/models/volumes.go
index 3d6aa4d74..2eddec52f 100644
--- a/pkg/models/volumes.go
+++ b/pkg/models/volumes.go
@@ -13,13 +13,13 @@ type PodListByPvc struct {
 	Pods      []v12.Pod `json:"pods"`
 }
 
+// List pods of a specific persistent volume claims
 func GetPodListByPvc(pvc string, ns string) (res []v12.Pod, err error) {
 	cli := client.NewK8sClient()
 	podList, err := cli.CoreV1().Pods(ns).List(v1.ListOptions{})
 	if err != nil {
 		return nil, err
 	}
-
 	for _, pod := range podList.Items {
 		if IsPvcInPod(pod, pvc) == true {
 			res = append(res, pod)
@@ -28,6 +28,7 @@ func GetPodListByPvc(pvc string, ns string) (res []v12.Pod, err error) {
 	return res, nil
 }
 
+// Check if the persistent volume claim is related to the pod
 func IsPvcInPod(pod v12.Pod, pvcname string) bool {
 	for _, v := range pod.Spec.Volumes {
 		if v.VolumeSource.PersistentVolumeClaim != nil &&