diff --git a/visualdl/logic/sdk.cc b/visualdl/logic/sdk.cc
index 33f00d42330c23bebab39ae6c159e9f24c5cd57c..94dce5c2bad3e200d8d08bb7294d6614a9b11f20 100644
--- a/visualdl/logic/sdk.cc
+++ b/visualdl/logic/sdk.cc
@@ -109,7 +109,7 @@ namespace components {
 template <typename T>
 std::vector<T> ScalarReader<T>::records() const {
   std::vector<T> res;
-  for (int i = 0; i < reader_.total_records(); i++) {
+  for (int i = 0; i < total_records(); i++) {
     res.push_back(reader_.record(i).data(0).template Get<T>());
   }
   return res;
@@ -302,7 +302,7 @@ void Histogram<T>::AddRecord(int step, const std::vector<T>& data) {
 
 template <typename T>
 HistogramRecord<T> HistogramReader<T>::record(int i) {
-  CHECK_LT(i, reader_.total_records());
+  CHECK_LT(i, num_records());
   auto r = reader_.record(i);
   auto d = r.data(0);
   auto boundaries_str = d.GetRaw();
diff --git a/visualdl/logic/sdk.h b/visualdl/logic/sdk.h
index 2fcc7f4240835cb2b8464e44e9694bc842db2580..810dc5c9f6314da9c05bfd6fb557e0d24b12c82c 100644
--- a/visualdl/logic/sdk.h
+++ b/visualdl/logic/sdk.h
@@ -126,7 +126,7 @@ struct ScalarReader {
   std::vector<T> ids() const;
   std::vector<T> timestamps() const;
   std::string caption() const;
-  size_t total_records() { return reader_.total_records(); }
+  size_t total_records() const { return reader_.total_records() - 1; }
   size_t size() const;
 
 private:
@@ -276,7 +276,7 @@ template <typename T>
 struct HistogramReader {
   HistogramReader(TabletReader tablet) : reader_(tablet) {}
 
-  size_t num_records() { return reader_.total_records(); }
+  size_t num_records() { return reader_.total_records() - 1; }
 
   HistogramRecord<T> record(int i);
 
diff --git a/visualdl/logic/sdk_test.cc b/visualdl/logic/sdk_test.cc
index dfda35b655c7e868144b33bdb27ea2a4008925f0..0a42ff23cf5ebd3f4d04e74a629f3311b112f64b 100644
--- a/visualdl/logic/sdk_test.cc
+++ b/visualdl/logic/sdk_test.cc
@@ -28,6 +28,7 @@ TEST(Scalar, write) {
   auto tablet = writer.AddTablet("scalar0");
   components::Scalar<int> scalar(tablet);
   scalar.AddRecord(0, 12);
+  scalar.AddRecord(1, 13);
   auto tablet1 = writer.AddTablet("model/layer/min");
   components::Scalar<float> scalar1(tablet1);
   scalar1.SetCaption("customized caption");
@@ -39,9 +40,11 @@ TEST(Scalar, write) {
   auto scalar_reader = components::ScalarReader<int>(std::move(tablet_reader));
   auto captioin = scalar_reader.caption();
   ASSERT_EQ(captioin, "train");
-  ASSERT_EQ(scalar_reader.total_records(), 1);
+  // reference PR#225
+  ASSERT_EQ(scalar_reader.total_records(), 2 - 1);
   auto record = scalar_reader.records();
-  ASSERT_EQ(record.size(), 1);
+  // reference PR#225
+  ASSERT_EQ(record.size(), 2 - 1);
   // check the first entry of first record
   ASSERT_EQ(record.front(), 12);
 
diff --git a/visualdl/python/test_storage.py b/visualdl/python/test_storage.py
index e2083fc3289bf33ea673ccd6336f12cf68740576..6c84c301fbdb62a59376253b97005762d57ba58e 100644
--- a/visualdl/python/test_storage.py
+++ b/visualdl/python/test_storage.py
@@ -29,7 +29,7 @@ class StorageTest(unittest.TestCase):
             records = scalar.records()
             ids = scalar.ids()
             self.assertTrue(
-                np.equal(records, [float(i) for i in range(10)]).all())
+                np.equal(records, [float(i) for i in range(10 - 1)]).all())
             self.assertTrue(np.equal(ids, [float(i) for i in range(10)]).all())
             print 'records', records
             print 'ids', ids
@@ -70,7 +70,7 @@ class StorageTest(unittest.TestCase):
         '''
         print 'check image'
         tag = "layer1/check/image1"
-        image_writer = self.writer.image(tag, 10, 1)
+        image_writer = self.writer.image(tag, 10)
 
         image = Image.open("./dog.jpg")
         shape = [image.size[1], image.size[0], 3]
@@ -81,6 +81,7 @@ class StorageTest(unittest.TestCase):
 
             image_writer.start_sampling()
             image_writer.add_sample(shape, list(origin_data))
+            image_writer.finish_sampling()
 
             # read and check whether the original image will be displayed
             image_reader = reader.image(tag)
diff --git a/visualdl/storage/tablet.h b/visualdl/storage/tablet.h
index e71cc9fef859d04dc4a4e62ebe941aa3a4dbb15d..03bb1fe678769752c2511ffa479ee00ed832fa12 100644
--- a/visualdl/storage/tablet.h
+++ b/visualdl/storage/tablet.h
@@ -115,7 +115,10 @@ struct TabletReader {
   Tablet::Type type() const { return Tablet::Type(data_.component()); }
   int64_t total_records() const { return data_.records_size(); }
   int32_t num_samples() const { return data_.num_samples(); }
-  RecordReader record(int i) const { return RecordReader(data_.records(i)); }
+  RecordReader record(int i) const {
+    CHECK_LT(i, total_records());
+    return RecordReader(data_.records(i));
+  }
   template <typename T>
   EntryReader meta() const {
     return EntryReader(data_.meta());