diff --git a/weed/storage/erasure_coding/389.ecx b/weed/storage/erasure_coding/389.ecx
new file mode 100644
index 000000000..158781920
Binary files /dev/null and b/weed/storage/erasure_coding/389.ecx differ
diff --git a/weed/storage/erasure_coding/ec_volume_test.go b/weed/storage/erasure_coding/ec_volume_test.go
new file mode 100644
index 000000000..66be2b997
--- /dev/null
+++ b/weed/storage/erasure_coding/ec_volume_test.go
@@ -0,0 +1,54 @@
+package erasure_coding
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/chrislusf/seaweedfs/weed/storage/needle"
+	"github.com/chrislusf/seaweedfs/weed/storage/types"
+)
+
+func TestPositioning(t *testing.T) {
+
+	ecxFile, err := os.OpenFile("389.ecx", os.O_RDONLY, 0)
+	if err != nil {
+		t.Errorf("failed to open ecx file: %v", err)
+	}
+	defer ecxFile.Close()
+
+	stat, _ := ecxFile.Stat()
+	fileSize := stat.Size()
+
+	tests := []struct {
+		needleId string
+		offset int64
+		size int
+	}{
+		{needleId: "0f0edb92", offset: 31300679656, size: 1167},
+		{needleId: "0ef7d7f8", offset: 11513014944, size: 66044},
+	}
+
+	for _, test := range tests {
+		needleId, _ := types.ParseNeedleId(test.needleId)
+		offset, size, err := SearchNeedleFromSortedIndex(ecxFile, fileSize, needleId, nil)
+		assert.Equal(t, nil, err, "SearchNeedleFromSortedIndex")
+		fmt.Printf("offset: %d size: %d\n", offset.ToAcutalOffset(), size)
+	}
+
+	needleId, _ := types.ParseNeedleId("0f087622")
+	offset, size, err := SearchNeedleFromSortedIndex(ecxFile, fileSize, needleId, nil)
+	assert.Equal(t, nil, err, "SearchNeedleFromSortedIndex")
+	fmt.Printf("offset: %d size: %d\n", offset.ToAcutalOffset(), size)
+
+	var shardEcdFileSize int64 = 1118830592 // 1024*1024*1024*3
+	intervals := LocateData(ErasureCodingLargeBlockSize, ErasureCodingSmallBlockSize, DataShardsCount*shardEcdFileSize, offset.ToAcutalOffset(), uint32(needle.GetActualSize(size, needle.CurrentVersion)))
+
+	for _, interval := range intervals {
+		shardId, shardOffset := interval.ToShardIdAndOffset(ErasureCodingLargeBlockSize, ErasureCodingSmallBlockSize)
+		fmt.Printf("interval: %+v, shardId: %d, shardOffset: %d\n", interval, shardId, shardOffset)
+	}
+
+}