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+<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
+<html>
+  <head>
+    <title>How to Relocate a File Data Structure</title>
+  </head>
+
+  <body>
+      <h1>How to Relocate a File Data Structure</h1>
+
+      <p>Since file data structures can be cached in memory by the H5AC
+	package it becomes problematic to move such a data structure in
+	the file. One cannot just copy a portion of the file from one
+	location to another because:
+
+      <ol>
+	<li>the file might not contain the latest information, and</li>
+	<li>the H5AC package might not realize that the object's
+	  address has changed and attempt to write the object to disk
+	  at the old address.</li>
+      </ol>
+      
+      <p>Here's a correct method to move data from one location to
+	another.  The example code assumes that one is moving a B-link
+	tree node from <code>old_addr</code> to <code>new_addr</code>.
+	
+      <ol>
+	<li>Make sure the disk is up-to-date with respect to the
+	  cache.  There is no need to remove the item from the cache,
+	  hence the final argument to <code>H5AC_flush</code> is
+	  <code>FALSE</code>.
+	  <br><br>
+	  <code>
+	    H5AC_flush (f, H5AC_BT, old_addr, FALSE);<br>
+	  </code>
+	  <br>
+	</li>
+	
+	<li>Read the data from the old address and write it to the new
+	  address.
+	  <br><br>
+	  <code>
+	    H5F_block_read (f, old_addr, size, buf);<br>
+	    H5F_block_write (f, new_addr, size, buf);<br>
+	  </code>
+	  <br>
+	</li>
+	  
+	<li>Notify the cache that the address of the object changed.
+	  <br><br>
+	  <code>
+	    H5AC_rename (f, H5AC_BT, old_addr, new_addr);<br>
+	  </code>
+	  <br>
+	</li>
+      </ol>
+	  
+
+
+      <hr>
+      <address><a href="mailto:robb@maya.nuance.com">Robb Matzke</a></address>
+<!-- Created: Mon Jul 14 15:09:06 EST 1997 -->
+<!-- hhmts start -->
+Last modified: Mon Jul 14 15:38:29 EST 
+<!-- hhmts end -->
+  </body>
+</html>