Added a comment and renamed the function

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OMDBCheckpointServlet.java

@@ -318,7 +318,7 @@ private boolean getFilesForArchive(DBCheckpoint checkpoint,
 
     // Get the snapshot files.
     Set<Path> snapshotPaths = waitForSnapshotDirs(checkpoint);
-    Path snapshotDir = Paths.get(getSnapshotsParentDir()).getParent();
+    Path snapshotDir = getSnapshotDir();
     if (!processDir(snapshotDir, copyFiles, hardLinkFiles, sstFilesToExclude,
         snapshotPaths, excluded, copySize, null)) {
       return false;
@@ -635,10 +635,13 @@ private OzoneConfiguration getConf() {
         .getConfiguration();
   }
 
-  private String getSnapshotsParentDir() {
+  private Path getSnapshotDir() {
     OzoneManager om = (OzoneManager) getServletContext().getAttribute(OzoneConsts.OM_CONTEXT_ATTRIBUTE);
     RDBStore store = (RDBStore) om.getMetadataManager().getStore();
-    return store.getSnapshotsParentDir();
+    // store.getSnapshotsParentDir() returns path to checkpointState (e.g. <om-data-dir>/db.snapshots/checkpointState)
+    // But we need to return path till db.snapshots which contains checkpointState and diffState.
+    // So that whole snapshots and compaction information can be transferred to follower.
+    return Paths.get(store.getSnapshotsParentDir()).getParent();
   }
 
   @Override