This code was used in a one-time migration script on Sitecore 7.2 (2014) // Parts are supplied by Sitecore.Support. No guarantees ;) // More context can be found here http://www.geekcore.nl/sitecore/extreme-sitecore-migration/

Sitecore Blobtransfer code

// This code was used in a one-time migration script on Sitecore 7.2 (2014)
// Parts are supplied by Sitecore.Support. No guarantees ;)
// More context can be found here http://www.geekcore.nl/sitecore/extreme-sitecore-migration/

      public class TransferMedia
    {
        public Sitecore.Data.Database migration
        {
            get
            {
                return Sitecore.Data.Database.GetDatabase("migration");
            }
        }

        protected Database ContentDatabase
        {
            get
            {
                Sitecore.Data.Database master = Sitecore.Configuration.Factory.GetDatabase("master");
                return master;
            }
        }

        public log4net.ILog logger = log4net.LogManager.GetLogger("Sitecore.Diagnostics.xxxxxxxxxxx");
        public StringBuilder Messages = new StringBuilder();
        
        public void TransferMediaFolder(Item siteRoot)
        {
            using (new SecurityDisabler())
            {
                Item mediaLibRootInMigration = migration.GetItem(Sitecore.ItemIDs.MediaLibraryRoot);
                
                Item mediaLibItem = mediaLibRootInMigration.Axes.GetChild(siteRoot.Name);
                if(mediaLibItem == null)
                {
                    // No media folder found!!
                    string nomedialibMessage = String.Format("No media library folder in migration DB found for '{0}'", siteRoot.Paths.FullPath);
                    Messages.AppendLine(nomedialibMessage);
                    logger.Info(nomedialibMessage);
                    return;

                }
                
                Item medialibRootInMaster = ContentDatabase.GetItem(Sitecore.ItemIDs.MediaLibraryRoot);

                TransferMediaNode(mediaLibItem, medialibRootInMaster, true);

                string successMessage = String.Format("Succesfully transferred media item library for '{0}'", siteRoot.Paths.FullPath);
                Messages.AppendLine(successMessage);
                logger.Info(successMessage);
            }
        }
        
        /// <summary>
        /// Transfers the items.
        /// 
        /// </summary>
        protected bool TransferMediaNode(Item sourceItem, Item destinationRoot, bool includeSubItems)
        {
            bool itemTransferred = false;


            if (sourceItem == null)
            {
                  // do something
            }

            if (destinationRoot == null)
            {
                  // do something
            }

        
    using (new ProxyDisabler())
        {
            string outerXml = sourceItem.GetOuterXml(includeSubItems);
          try
          {
              ItemTransferringCapsule capsule = new ItemTransferringCapsule(sourceItem.Database, destinationRoot.Database);
            try
            {
              Event.Subscribe("item:saved", new EventHandler(BlobTransferrer.TransferBlobOnSave));
              using (new ItemTransferringContext(capsule))
                  destinationRoot.Paste(outerXml, false, PasteMode.Overwrite);
            }
            finally
            {
              Event.Unsubscribe("item:saved", new EventHandler(BlobTransferrer.TransferBlobOnSave));
            }
          }
          catch (TemplateNotFoundException ex)
          {
               // log /throw error
          }
    }
           
         
            return itemTransferred;
        }
    }
    
    public class ItemTransferringCapsule
    {
        public Database SourceDb { get; set; }

        public Database TargetDb { get; set; }

        public ItemTransferringCapsule(Database sourceDb, Database targetDb)
        {
            this.SourceDb = sourceDb;
            this.TargetDb = targetDb;
        }
    }

    public class ItemTransferringContext : Switcher<ItemTransferringCapsule>
    {
        public ItemTransferringContext(ItemTransferringCapsule capsule)
            : base(capsule)
        {
        }
    }


  
  
  public class BlobTransferrer
    {
        public static log4net.ILog logger = log4net.LogManager.GetLogger("Sitecore.Diagnostics.xxxxxxxxx");

        public static void TransferBlobOnSave(object sender, EventArgs e)
        {
            ItemTransferringCapsule currentValue = Switcher<ItemTransferringCapsule, ItemTransferringCapsule>.CurrentValue;
            if (currentValue == null)
                return;
            Item obj = SitecoreEventArgs.GetItem(e, 0);
            Assert.IsNotNull((object)obj, "Item cannot be null");
            List<Guid> blobIds = new List<Guid>();

            if (obj.Template != null)
            {
                foreach (TemplateField templateField in TemplateManager.GetTemplate(obj).GetFields())
                {
                    if (templateField.IsBlob)
                    {
                        string str = obj.Fields[templateField.ID].GetValue(true);
                        if (!StringExtensions.IsNullOrEmpty(str) && MainUtil.IsID(str))
                            blobIds.Add(new Guid(str));
                    }
                }
            }
            else
            {
                // No media folder found!!
                string noTemplateMessage = String.Format("No template found for item: '{0}'", obj.Paths.FullPath);
                logger.Info(noTemplateMessage);
            }
            if (blobIds.Count <= 0)
                return;
            BlobTransferrer.PerformBlobsTransfer(blobIds, currentValue);
        }

        private static void PerformBlobsTransfer(List<Guid> blobIds, ItemTransferringCapsule currentCapsule)
        {
            foreach (Guid blobId in blobIds)
            {
                if (!ItemManager.BlobStreamExists(blobId, currentCapsule.TargetDb))
                {
                    using (Stream blobStream = ItemManager.GetBlobStream(blobId, currentCapsule.SourceDb))
                        ItemManager.SetBlobStream(blobStream, blobId, currentCapsule.TargetDb);
                }
            }
        }
    }