diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 47228a47799..9e1dc17287e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -735,6 +735,9 @@ Release 2.7.0 - UNRELEASED
 
     HDFS-7637. Fix the check condition for reserved path. (Yi Liu via jing9)
 
+    HDFS-7634. Disallow truncation of Lazy persist files. (Yi Liu via
+    Arpit Agarwal)
+
 Release 2.6.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
index ff53fb5ddc5..6a8f57452de 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
@@ -1952,6 +1952,14 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
       dir.checkPathAccess(pc, iip, FsAction.WRITE);
     }
     INodeFile file = INodeFile.valueOf(iip.getLastINode(), src);
+    final BlockStoragePolicy lpPolicy =
+        blockManager.getStoragePolicy("LAZY_PERSIST");
+
+    if (lpPolicy != null &&
+        lpPolicy.getId() == file.getStoragePolicyID()) {
+      throw new UnsupportedOperationException(
+          "Cannot truncate lazy persist file " + src);
+    }
     // Opening an existing file for write. May need lease recovery.
     recoverLeaseInternal(iip, src, clientName, clientMachine, false);
     // Truncate length check.