diff --git a/packages/xo-server/uploadVhd.py b/packages/xo-server/uploadVhd.py
index 1b6ac8d54..ab59ee169 100644
--- a/packages/xo-server/uploadVhd.py
+++ b/packages/xo-server/uploadVhd.py
@@ -8,6 +8,19 @@ import math
 
 # inspired from https://github.com/imcleod/pyvhd/blob/master/pyvhd.py
 
+class FakeSocket:
+
+    def __init__(self):
+        self.sent = 0
+    
+    def connect(self, host):
+        #nothin to do 
+        print('connected')
+
+    def send(self, data):
+        # nothing to be done
+        self.sent += len(data)
+
 
 def divro(num, den):
     # Divide always rounding up and returning an integer
@@ -155,15 +168,17 @@ class Vhd:
 
         batOffset = self.parsedHeader[2]
         print('batOffset',batOffset)
-        self.file.seek(batOffset)
-        batLength = self.parsedHeader[4]
+        self.parentLocator = self.file.read(batOffset - self.parsedFooter[3] - 1024)
+        print('parentLocator', len(self.parentLocator))
+        batLength = self.parsedHeader[4] * 4
         print('batlnght',batLength)
-        
-        self.file.seek(batOffset)
+
         bat = self.file.read(batLength*4)
+        # realign to 512 bytes sectors
+        self.file.seek(math.ceil((batLength + batOffset)/512)*512)
         self.bat= []
 
-        for blockIndex in range(0,batLength) :
+        for blockIndex in range(0,batLength/4) :
             offset = struct.unpack_from('>I', bat, blockIndex * 4)[0]
             self.bat.append(offset)
 
@@ -181,6 +196,7 @@ class Vhd:
         else:
             print('found root')
             self.parent = None
+
     
     def containsBlocks(self, index):
         return self.bat[index] != 0xffffffff or ( self.parent and self.parent.containsBlocks(index) )
@@ -219,37 +235,44 @@ class Vhd:
         struct.pack_into(">I", footer, 64, 0 )
         struct.pack_into('>I', footer, 64, (vhd_checksum(footer)))
         sent = 0
+        print('will send footer', len(footer), sent)
         socket.send(footer)
         sent += len(footer)
 
         # write child header but with root parentTimestamp,parentUnicodeName,parentUuid
-        header = header[0:40] +  root.header[40: 558] + header[558:]
+        header = header[0:40] +  root.header[40:] 
         # todo checksum 
         struct.pack_into(">I", header, 36, 0 ) 
         struct.pack_into('>I', header, 36, (vhd_checksum(header)))
+        print('will send header', len(header), sent)
         socket.send(header)
         sent += len(header)
 
+        # parent locator : ignore for now 
+        print('will send PL', len(root.parentLocator), sent)
+        socket.send(root.parentLocator)
+        sent += len(root.parentLocator)
+
         # write BAT aligned with 512bytes sector
 
-        offset = 1024 + 512  + len(self.bat) * 4 
-        offsetSector = math.ceil(offset/512)
+        offset = sent  + len(self.bat)*4
+        offsetSector = int(math.ceil(offset/512))
         bat = ""
+        print("start", offsetSector, sent, len(self.bat))*4
         for blockIndex in range(0, len(self.bat), 1):
             if self.containsBlocks(blockIndex) :
-                #print('got block', blockIndex)
-                bat += struct.pack(">I", ( offsetSector ) )
+                bat += struct.pack("I", ( offsetSector ) )
                 offsetSector += 4*1024 + 1
             else:
                 bat += struct.pack(">I", 0xffffffff )
 
 #        add padding to align to 512 bytes
         while len(bat) % 512 !=0:
+            print("pad", len(bat))
             bat += struct.pack(">I", ( 0 ) )
+        print('will send BAT', len(bat), sent)
         socket.send(bat)
-        print('bat len', len(bat))
         sent += len(bat)
-        
         # todo : parent locator 
 
         # write blocks
@@ -257,7 +280,6 @@ class Vhd:
             data = self.getBlockData(blockIndex)
             # print('will send ', len(data), blockIndex, len(self.bat))
             if data:
-                # print(' got data for block ', blockIndex) 
                 socket.send(data)
                 sent += len(data)
 
@@ -313,6 +335,7 @@ def main():
     vhd = Vhd(args.file_path)
 
     client_socket = socket.socket()
+#    client_socket = FakeSocket()
     client_socket.connect((args.host, int(args.port)))
     vhd.writeTo(client_socket)
 #    send(args.host, args.port, args.key, root_path)