diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/Storage.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/Storage.java
index 009d0f03e57..b0fe2900591 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/Storage.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/Storage.java
@@ -124,7 +124,7 @@ public abstract class Storage extends StorageInfo {
   }
 
   protected List<StorageDirectory> storageDirs =
-      new CopyOnWriteArrayList<StorageDirectory>();
+      new CopyOnWriteArrayList<>();
   
   private class DirIterator implements Iterator<StorageDirectory> {
     final StorageDirType dirType;
@@ -879,7 +879,11 @@ public abstract class Storage extends StorageInfo {
   public int getNumStorageDirs() {
     return storageDirs.size();
   }
-  
+
+  public List<StorageDirectory> getStorageDirs() {
+    return storageDirs;
+  }
+
   public StorageDirectory getStorageDir(int idx) {
     return storageDirs.get(idx);
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceStorage.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceStorage.java
index 81fce6f621b..a7edb4b6002 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceStorage.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceStorage.java
@@ -292,7 +292,7 @@ public class BlockPoolSliceStorage extends Storage {
   void remove(File absPathToRemove) {
     Preconditions.checkArgument(absPathToRemove.isAbsolute());
     LOG.info("Removing block level storage: " + absPathToRemove);
-    for (Iterator<StorageDirectory> it = this.storageDirs.iterator();
+    for (Iterator<StorageDirectory> it = getStorageDirs().iterator();
          it.hasNext(); ) {
       StorageDirectory sd = it.next();
       if (sd.getRoot().getAbsoluteFile().equals(absPathToRemove)) {
@@ -772,7 +772,7 @@ public class BlockPoolSliceStorage extends Storage {
    */
   public void clearTrash() {
     final List<File> trashRoots = new ArrayList<>();
-    for (StorageDirectory sd : storageDirs) {
+    for (StorageDirectory sd : getStorageDirs()) {
       File trashRoot = getTrashRootDir(sd);
       if (trashRoot.exists() && sd.getPreviousDir().exists()) {
         LOG.error("Trash and PreviousDir shouldn't both exist for storage "
@@ -810,7 +810,7 @@ public class BlockPoolSliceStorage extends Storage {
   /** trash is enabled if at least one storage directory contains trash root */
   @VisibleForTesting
   public boolean trashEnabled() {
-    for (StorageDirectory sd : storageDirs) {
+    for (StorageDirectory sd : getStorageDirs()) {
       if (getTrashRootDir(sd).exists()) {
         return true;
       }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java
index 0a8f1fef3e2..a1abfcefca2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java
@@ -188,11 +188,11 @@ public class DataStorage extends Storage {
   }
 
   public void setRollingUpgradeMarker(String bpid) throws IOException {
-    getBPStorage(bpid).setRollingUpgradeMarkers(storageDirs);
+    getBPStorage(bpid).setRollingUpgradeMarkers(getStorageDirs());
   }
 
   public void clearRollingUpgradeMarker(String bpid) throws IOException {
-    getBPStorage(bpid).clearRollingUpgradeMarkers(storageDirs);
+    getBPStorage(bpid).clearRollingUpgradeMarkers(getStorageDirs());
   }
 
   /**
@@ -505,7 +505,7 @@ public class DataStorage extends Storage {
     }
 
     StringBuilder errorMsgBuilder = new StringBuilder();
-    for (Iterator<StorageDirectory> it = this.storageDirs.iterator();
+    for (Iterator<StorageDirectory> it = getStorageDirs().iterator();
          it.hasNext(); ) {
       StorageDirectory sd = it.next();
       if (dirsToRemove.contains(sd.getRoot())) {
@@ -1027,7 +1027,7 @@ public class DataStorage extends Storage {
     // To handle finalizing a snapshot taken at datanode level while
     // upgrading to federation, if datanode level snapshot previous exists, 
     // then finalize it. Else finalize the corresponding BP.
-    for (StorageDirectory sd : storageDirs) {
+    for (StorageDirectory sd : getStorageDirs()) {
       File prevDir = sd.getPreviousDir();
       if (prevDir.exists()) {
         // data node level storage finalize
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java
index 6290c431ecd..a8f998c2966 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java
@@ -167,8 +167,6 @@ public class NNStorage extends Storage implements Closeable,
       throws IOException {
     super(NodeType.NAME_NODE);
 
-    storageDirs = new CopyOnWriteArrayList<StorageDirectory>();
-    
     // this may modify the editsDirs, so copy before passing in
     setStorageDirectories(imageDirs, 
                           Lists.newArrayList(editsDirs),
@@ -206,7 +204,7 @@ public class NNStorage extends Storage implements Closeable,
   @Override // Closeable
   public void close() throws IOException {
     unlockAll();
-    storageDirs.clear();
+    getStorageDirs().clear();
   }
 
   /**
@@ -291,7 +289,7 @@ public class NNStorage extends Storage implements Closeable,
                                           Collection<URI> fsEditsDirs,
                                           Collection<URI> sharedEditsDirs)
       throws IOException {
-    this.storageDirs.clear();
+    getStorageDirs().clear();
     this.removedStorageDirs.clear();
 
    // Add all name dirs with appropriate NameNodeDirType
@@ -863,7 +861,7 @@ public class NNStorage extends Storage implements Closeable,
                +  sd.getRoot().getPath(), e);
     }
 
-    if (this.storageDirs.remove(sd)) {
+    if (getStorageDirs().remove(sd)) {
       this.removedStorageDirs.add(sd);
     }
     
@@ -917,7 +915,7 @@ public class NNStorage extends Storage implements Closeable,
     // getCanonicalPath may need to call stat() or readlink() and it's likely
     // those calls would fail due to the same underlying IO problem.
     String absPath = f.getAbsolutePath();
-    for (StorageDirectory sd : storageDirs) {
+    for (StorageDirectory sd : getStorageDirs()) {
       String dirPath = sd.getRoot().getAbsolutePath();
       if (!dirPath.endsWith(File.separator)) {
         dirPath += File.separator;
@@ -1125,14 +1123,14 @@ public class NNStorage extends Storage implements Closeable,
   @Override
   public void writeAll() throws IOException {
     this.layoutVersion = getServiceLayoutVersion();
-    for (StorageDirectory sd : storageDirs) {
+    for (StorageDirectory sd : getStorageDirs()) {
       try {
         writeProperties(sd);
       } catch (Exception e) {
         LOG.warn("Error during write properties to the VERSION file to " +
             sd.toString(), e);
         reportErrorsOnDirectory(sd);
-        if (storageDirs.isEmpty()) {
+        if (getStorageDirs().isEmpty()) {
           throw new IOException("All the storage failed while writing " +
               "properties to VERSION file");
         }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/common/StorageAdapter.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/common/StorageAdapter.java
index 3dd81b257f9..c2df9bf9128 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/common/StorageAdapter.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/common/StorageAdapter.java
@@ -33,7 +33,7 @@ public abstract class StorageAdapter {
       Storage s, int idx) {
 
     StorageDirectory dir = Mockito.spy(s.getStorageDir(idx));
-    s.storageDirs.set(idx, dir);
+    s.getStorageDirs().set(idx, dir);
     return dir;
   }
 }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestBlockPoolSliceStorage.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestBlockPoolSliceStorage.java
index b5951a0aad2..0371b4c2e55 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestBlockPoolSliceStorage.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestBlockPoolSliceStorage.java
@@ -49,7 +49,7 @@ public class TestBlockPoolSliceStorage {
                               String clusterId) {
       super(namespaceID, bpID, cTime, clusterId);
       addStorageDir(new StorageDirectory(new File("/tmp/dontcare/" + bpID)));
-      assertThat(storageDirs.size(), is(1));
+      assertThat(getStorageDirs().size(), is(1));
     }
   }