Index: lucene/src/test/org/apache/lucene/index/TestIndexWriter.java
===================================================================
--- lucene/src/test/org/apache/lucene/index/TestIndexWriter.java	(revision 981649)
+++ lucene/src/test/org/apache/lucene/index/TestIndexWriter.java	(working copy)
@@ -5070,56 +5070,61 @@
   }
 
   public void testRandomStoredFields() throws IOException {
-    Directory dir = new MockRAMDirectory();
-    Random rand = newRandom();
-    RandomIndexWriter w = new RandomIndexWriter(rand, dir, newIndexWriterConfig(rand, TEST_VERSION_CURRENT, new MockAnalyzer()).setMaxBufferedDocs(_TestUtil.nextInt(rand, 5, 20)));
-    final int docCount = 200*RANDOM_MULTIPLIER;
-    final int fieldCount = _TestUtil.nextInt(rand, 1, 5);
-    String[][] fields = new String[fieldCount][];
-    for(int i=0;i<fieldCount;i++) {
-      fields[i] = new String[docCount];
-    }
+    File index = _TestUtil.getTempDir("lucenerandfields");
+    Directory dir = FSDirectory.open(index);
+    try {
+      Random rand = newRandom();
+      RandomIndexWriter w = new RandomIndexWriter(rand, dir, newIndexWriterConfig(rand, TEST_VERSION_CURRENT, new MockAnalyzer()).setMaxBufferedDocs(_TestUtil.nextInt(rand, 5, 20)));
+      final int docCount = 200*RANDOM_MULTIPLIER;
+      final int fieldCount = _TestUtil.nextInt(rand, 1, 5);
+      String[][] fields = new String[fieldCount][];
+      for(int i=0;i<fieldCount;i++) {
+        fields[i] = new String[docCount];
+      }
 
-    final List<Integer> fieldIDs = new ArrayList<Integer>();
+      final List<Integer> fieldIDs = new ArrayList<Integer>();
 
-    for(int i=0;i<fieldCount;i++) {
-      fieldIDs.add(i);
-    }
+      for(int i=0;i<fieldCount;i++) {
+        fieldIDs.add(i);
+      }
     
-    for(int i=0;i<docCount;i++) {
-      Document doc = new Document();
-      for(int field: fieldIDs) {
-        final String s;
-        if (rand.nextInt(4) != 3) {
-          s = _TestUtil.randomUnicodeString(rand, 1000);
-          doc.add(new Field("f"+field, s, Field.Store.YES, Field.Index.NO));
-        } else {
-          s = null;
+      for(int i=0;i<docCount;i++) {
+        Document doc = new Document();
+        for(int field: fieldIDs) {
+          final String s;
+          if (rand.nextInt(4) != 3) {
+            s = _TestUtil.randomUnicodeString(rand, 1000);
+            doc.add(new Field("f"+field, s, Field.Store.YES, Field.Index.NO));
+          } else {
+            s = null;
+          }
+          fields[field][i] = s;
         }
-        fields[field][i] = s;
+        w.addDocument(doc);
+        if (rand.nextInt(50) == 17) {
+          // mixup binding of field name -> Number every so often
+          Collections.shuffle(fieldIDs);
+        }
       }
-      w.addDocument(doc);
-      if (rand.nextInt(50) == 17) {
-        // mixup binding of field name -> Number every so often
-        Collections.shuffle(fieldIDs);
-      }
-    }
 
-    for(int x=0;x<2;x++) {
-      IndexReader r = w.getReader();
+      for(int x=0;x<2;x++) {
+        IndexReader r = w.getReader();
 
-      for(int iter=0;iter<1000*RANDOM_MULTIPLIER;iter++) {
-        int docID = rand.nextInt(docCount);
-        Document doc = r.document(docID);
-        for(int i=0;i<fieldCount;i++) {
-          assertEquals(fields[i][docID], doc.get("f"+i));
+        for(int iter=0;iter<1000*RANDOM_MULTIPLIER;iter++) {
+          int docID = rand.nextInt(docCount);
+          Document doc = r.document(docID);
+          for(int i=0;i<fieldCount;i++) {
+            assertEquals(fields[i][docID], doc.get("f"+i));
+          }
         }
+        r.close();
+        w.optimize();
       }
-      r.close();
-      w.optimize();
+      w.close();
+
+    } finally {
+      dir.close();
+      _TestUtil.rmDir(index);
     }
-    w.close();
-
-    dir.close();
   }
 }
Index: lucene/src/java/org/apache/lucene/store/FSDirectory.java
===================================================================
--- lucene/src/java/org/apache/lucene/store/FSDirectory.java	(revision 981649)
+++ lucene/src/java/org/apache/lucene/store/FSDirectory.java	(working copy)
@@ -475,6 +475,10 @@
       
       // do the optimized copy
       FileChannel in = fsInput.file.getChannel();
+
+      // Necessary because BufferedIndexInput does lazy seeking:
+      in.position(fsInput.getFilePointer());
+
       FileChannel out = file.getChannel();
       long pos = out.position();
       long writeTo = numBytes + pos;