diff --git a/[refs] b/[refs]
index 8ae13611a234a..09b5fef92bf6d 100644
--- a/[refs]
+++ b/[refs]
@@ -1,3 +1,3 @@
 ---
 refs/heads/gh-pages: ac155dadd83efa75cad55c0508a57a2b9dd3d66c
-"refs/heads/CMSSW_7_1_X": 4797eccd42d4cf15638cf44dddb37faf1e97f1c4
+"refs/heads/CMSSW_7_1_X": 341ba6c01d00fb5eb89bc9658a0c17d301dbeefd
diff --git a/trunk/Utilities/StorageFactory/interface/LocalCacheFile.h b/trunk/Utilities/StorageFactory/interface/LocalCacheFile.h
new file mode 100644
index 0000000000000..6add850717600
--- /dev/null
+++ b/trunk/Utilities/StorageFactory/interface/LocalCacheFile.h
@@ -0,0 +1,43 @@
+#ifndef STORAGE_FACTORY_LOCAL_CACHE_FILE_H
+# define STORAGE_FACTORY_LOCAL_CACHE_FILE_H
+
+# include "Utilities/StorageFactory/interface/Storage.h"
+# include "Utilities/StorageFactory/interface/File.h"
+# include <vector>
+# include <string>
+
+/** Proxy class to copy a file locally in large chunks. */
+class LocalCacheFile : public Storage
+{
+public:
+  LocalCacheFile (Storage *base);
+  ~LocalCacheFile (void);
+
+  using Storage::read;
+  using Storage::write;
+
+  virtual bool		prefetch (const IOPosBuffer *what, IOSize n);
+  virtual IOSize	read (void *into, IOSize n);
+  virtual IOSize	read (void *into, IOSize n, IOOffset pos);
+  virtual IOSize	readv (IOBuffer *into, IOSize n);
+  virtual IOSize	readv (IOPosBuffer *into, IOSize n);
+  virtual IOSize	write (const void *from, IOSize n);
+  virtual IOSize	write (const void *from, IOSize n, IOOffset pos);
+  virtual IOSize	writev (const IOBuffer *from, IOSize n);
+  virtual IOSize	writev (const IOPosBuffer *from, IOSize n);
+
+  virtual IOOffset	position (IOOffset offset, Relative whence = SET);
+  virtual void		resize (IOOffset size);
+  virtual void		flush (void);
+  virtual void		close (void);
+
+private:
+  void			cache (IOOffset start, IOOffset end);
+
+  IOOffset		image_;
+  std::vector<bool>	present_;
+  File			*file_;
+  Storage		*storage_;
+};
+
+#endif // STORAGE_FACTORY_LOCAL_CACHE_FILE_H
diff --git a/trunk/Utilities/StorageFactory/src/LocalCacheFile.cc b/trunk/Utilities/StorageFactory/src/LocalCacheFile.cc
new file mode 100644
index 0000000000000..cd820eaa7bc43
--- /dev/null
+++ b/trunk/Utilities/StorageFactory/src/LocalCacheFile.cc
@@ -0,0 +1,183 @@
+#include "Utilities/StorageFactory/interface/LocalCacheFile.h"
+#include "Utilities/StorageFactory/interface/File.h"
+#include "FWCore/Utilities/interface/EDMException.h"
+#include <utility>
+#include <iostream>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <errno.h>
+
+static const IOOffset CHUNK_SIZE = 128*1024*1024;
+
+static void
+nowrite(const char *why)
+{
+  throw cms::Exception("LocalCacheFile")
+    << "Cannot change file but operation '" << why << "' was called";
+}
+
+
+LocalCacheFile::LocalCacheFile(Storage *base)
+  : image_(base->size()),
+    file_(0),
+    storage_(base)
+{
+  present_.resize((image_ + CHUNK_SIZE - 1) / CHUNK_SIZE, false);
+
+  std::string pattern("/tmp");
+  if (char *p = getenv("TMPDIR"))
+    pattern = p;
+  pattern += "/cmssw-shadow-XXXXXX";
+
+  std::vector<char> temp(pattern.c_str(), pattern.c_str()+pattern.size()+1);
+  int fd = mkstemp(&temp[0]);
+  if (fd == -1)
+    throw cms::Exception("LocalCacheFile")
+      << "Cannot create temporary file '" << pattern << "': "
+      << strerror(errno) << " (error " << errno << ")";
+
+  unlink(&temp[0]);
+  file_ = new File(fd);
+  file_->resize(image_);
+}
+
+LocalCacheFile::~LocalCacheFile(void)
+{
+  delete file_;
+  delete storage_;
+}
+
+void
+LocalCacheFile::cache(IOOffset start, IOOffset end)
+{
+  start = (start / CHUNK_SIZE) * CHUNK_SIZE;
+  end = std::min(end, image_);
+  while (start < end)
+  {
+    IOSize nread = 0;
+    IOSize index = start / CHUNK_SIZE;
+    IOSize len = std::min(image_ - start, CHUNK_SIZE);
+    if (! present_[index])
+    {
+      void *window = mmap(0, len, PROT_READ | PROT_WRITE, MAP_SHARED, file_->fd(), start);
+      if (window == MAP_FAILED)
+        throw cms::Exception("LocalCacheFile")
+	  << "Unable to map a window of local cache file: "
+	  << strerror(errno) << " (error " << errno << ")";
+
+      try
+      {
+        nread = storage_->read(window, len, start);
+      }
+      catch (cms::Exception &e)
+      {
+        munmap(window, len);
+        throw cms::Exception("LocalCacheFile")
+	  << "Unable to cache " << len << " byte file segment at " << start
+	  << ": " << e.what();
+      }
+
+      munmap(window, len);
+
+      if (nread != len)
+        throw cms::Exception("LocalCacheFile")
+          << "Unable to cache " << len << " byte file segment at " << start
+	  << ": got only " << nread << " bytes back";
+
+      present_[index] = true;
+    }
+
+    start += len;
+  }
+}
+
+IOSize
+LocalCacheFile::read(void *into, IOSize n)
+{
+  IOOffset here = file_->position();
+  cache(here, here + n);
+
+  return file_->read(into, n);
+}
+
+IOSize
+LocalCacheFile::read(void *into, IOSize n, IOOffset pos)
+{
+  cache(pos, pos + n);
+  return file_->read(into, n, pos);
+}
+
+IOSize
+LocalCacheFile::readv(IOBuffer *into, IOSize n)
+{
+  IOOffset start = file_->position();
+  IOOffset end = start;
+  for (IOSize i = 0; i < n; ++i)
+    end += into[i].size();
+  cache(start, end);
+
+  return file_->readv(into, n);
+}
+
+IOSize
+LocalCacheFile::readv(IOPosBuffer *into, IOSize n)
+{
+  for (IOSize i = 0; i < n; ++i)
+  {
+    IOOffset start = into[i].offset();
+    IOOffset end = start + into[i].size();
+    cache(start, end);
+  }
+
+  return storage_->readv(into, n);
+}
+
+IOSize
+LocalCacheFile::write(const void *from, IOSize n)
+{ nowrite("write"); return 0; }
+
+IOSize
+LocalCacheFile::write(const void *from, IOSize n, IOOffset pos)
+{ nowrite("write"); return 0; }
+
+IOSize
+LocalCacheFile::writev(const IOBuffer *from, IOSize n)
+{ nowrite("writev"); return 0; }
+
+IOSize
+LocalCacheFile::writev(const IOPosBuffer *from, IOSize n)
+{ nowrite("writev"); return 0; }
+
+IOOffset
+LocalCacheFile::position(IOOffset offset, Relative whence)
+{ return file_->position(offset, whence); }
+
+void
+LocalCacheFile::resize(IOOffset size)
+{ nowrite("resize"); }
+
+void
+LocalCacheFile::flush(void)
+{ nowrite("flush"); }
+
+void
+LocalCacheFile::close(void)
+{
+  storage_->close();
+  file_->close();
+}
+
+bool
+LocalCacheFile::prefetch(const IOPosBuffer *what, IOSize n)
+{
+  for (IOSize i = 0; i < n; ++i)
+  {
+    IOOffset start = what[i].offset();
+    IOOffset end = start + what[i].size();
+    cache(start, end);
+  }
+  
+  return file_->prefetch(what, n);
+}