[svn-r730] Changes since 19980928

----------------------

./MANIFEST
	Changed freebsd2.2.1 to freebsd2.2.7 to match change in file name.

	Added a few missing files.  Are all of these supposed to be
	distributed?

	  ./tools/testfiles/h5dumptst.c
	+ ./tools/testfiles/tall-1.ddl
	+ ./tools/testfiles/tall-2.ddl
	+ ./tools/testfiles/tall-3.ddl
	  ./tools/testfiles/tall.ddl
	  ./tools/testfiles/tall.h5
	+ ./tools/testfiles/tattr-1.ddl
	+ ./tools/testfiles/tattr-2.ddl
	+ ./tools/testfiles/tattr-3.ddl
	+ ./tools/testfiles/tattr-4.ddl
	  ./tools/testfiles/tattr.ddl
	  ./tools/testfiles/tattr.h5
	+ ./tools/testfiles/tdset-1.ddl
	+ ./tools/testfiles/tdset-2.ddl
	+ ./tools/testfiles/tdset-3.ddl
	+ ./tools/testfiles/tdset-4.ddl
	  ./tools/testfiles/tdset.ddl
	  ./tools/testfiles/tdset.h5
	+ ./tools/testfiles/tgroup-1.ddl
	+ ./tools/testfiles/tgroup-2.ddl
	+ ./tools/testfiles/tgroup-3.ddl
	  ./tools/testfiles/tgroup.ddl
	  ./tools/testfiles/tgroup.h5
	+ ./tools/testfiles/tslink-1.ddl
	+ ./tools/testfiles/tslink-2.ddl
	  ./tools/testfiles/tslink.ddl
	  ./tools/testfiles/tslink.h5

./src/H5B.c
./src/H5Bprivate.h
./src/H5D.c
./src/H5Dprivate.h
./src/H5Farray.c
./src/H5Fistore.c
./src/H5Fprivate.h
./src/H5Gstab.c
./src/H5P.c
./src/H5Ppublic.h
./src/H5Sall.c
./src/H5Shyper.c
./src/H5Spoint.c
./src/H5Sprivate.h
./test/istore.c
	Implemented split ratios as documented in previous
	e-mails. Frank, the new API functions are H5Pget_btree_ratios()
	and H5Pset_btree_ratios().

./src/H5Sall.c
./src/H5Shyper.c
./src/H5Spoint.c
./src/H5Sprivate.h
	Added more type checking for the data transfer property list
	passed to these functions.

./src/H5D.c
	Added a dataset transfer property list as an argument to
	H5D_allocate() for the parallel version in order to pass split
	ratios down to H5F_istore_lock().  Eventually we won't need
	the split ratios for H5D_allocate() because we'll build a
	completely full B-tree from the leaves up, but it might be
	useful to have other transfer properties at that level
	anyway.  I always caled H5D_allocate() with &H5D_dflt_xfer.

./MANIFEST
./test/Makefile.in
./test/overhead.c	[NEW]
	Added an `overhead' test run by `make timings'.

15 files changed, 538 insertions, 293 deletions

diff --git a/src/H5B.c b/src/H5B.c
index 5546140..0bab777 100644
--- a/src/H5B.c
+++ b/src/H5B.c
@@ -102,6 +102,7 @@
 /* PRIVATE PROTOTYPES */
 static H5B_ins_t H5B_insert_helper(H5F_t *f, const haddr_t *addr,
 				   const H5B_class_t *type,
+				   const double split_ratios[],
 				   uint8 *lt_key,
 				   hbool_t *lt_key_changed,
 				   uint8 *md_key, void *udata,
@@ -121,8 +122,9 @@ static herr_t H5B_decode_keys(H5F_t *f, H5B_t *bt, intn idx);
 static size_t H5B_nodesize(H5F_t *f, const H5B_class_t *type,
 			   size_t *total_nkey_size, size_t sizeof_rkey);
 static herr_t H5B_split(H5F_t *f, const H5B_class_t *type,
-			H5B_t *old_bt, const haddr_t *old_addr,
-			void *udata, haddr_t *new_addr /*out*/ );
+			H5B_t *old_bt, const haddr_t *old_addr, intn idx,
+			const double split_ratios[], void *udata,
+			haddr_t *new_addr/*out*/);
 #ifdef H5B_DEBUG
 static herr_t H5B_assert(H5F_t *f, const haddr_t *addr,
 			 const H5B_class_t *type, void *udata);
@@ -259,6 +261,7 @@ H5B_create(H5F_t *f, const H5B_class_t *type, void *udata,
     
     FUNC_LEAVE(ret_value);
 }
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5B_load
@@ -280,12 +283,12 @@ H5B_create(H5F_t *f, const H5B_class_t *type, void *udata,
 static H5B_t *
 H5B_load(H5F_t *f, const haddr_t *addr, const void *_type, void *udata)
 {
-    const H5B_class_t	   *type = (const H5B_class_t *) _type;
-    size_t		    size, total_nkey_size;
-    H5B_t		   *bt = NULL;
-    intn		    i;
-    uint8		   *p;
-    H5B_t		   *ret_value = NULL;
+    const H5B_class_t	*type = (const H5B_class_t *) _type;
+    size_t		size, total_nkey_size;
+    H5B_t		*bt = NULL;
+    intn		i;
+    uint8		*p;
+    H5B_t		*ret_value = NULL;
 
     FUNC_ENTER(H5B_load, NULL);
 
@@ -391,9 +394,9 @@ H5B_load(H5F_t *f, const haddr_t *addr, const void *_type, void *udata)
 static herr_t
 H5B_flush(H5F_t *f, hbool_t destroy, const haddr_t *addr, H5B_t *bt)
 {
-    intn		    i;
-    size_t		    size = 0;
-    uint8		   *p = bt->page;
+    intn	i;
+    size_t	size = 0;
+    uint8	*p = bt->page;
 
     FUNC_ENTER(H5B_flush, FAIL);
 
@@ -506,9 +509,9 @@ H5B_flush(H5F_t *f, hbool_t destroy, const haddr_t *addr, H5B_t *bt)
 herr_t
 H5B_find(H5F_t *f, const H5B_class_t *type, const haddr_t *addr, void *udata)
 {
-    H5B_t		   *bt = NULL;
-    intn		    idx = -1, lt = 0, rt, cmp = 1;
-    int			    ret_value = FAIL;
+    H5B_t	*bt = NULL;
+    intn	idx = -1, lt = 0, rt, cmp = 1;
+    int		ret_value = FAIL;
 
     FUNC_ENTER(H5B_find, FAIL);
 
@@ -605,12 +608,13 @@ H5B_find(H5F_t *f, const H5B_class_t *type, const haddr_t *addr, void *udata)
  */
 static herr_t
 H5B_split(H5F_t *f, const H5B_class_t *type, H5B_t *old_bt,
-	  const haddr_t *old_addr, void *udata, haddr_t *new_addr /*out */ )
+	  const haddr_t *old_addr, intn idx, const double split_ratios[],
+	  void *udata, haddr_t *new_addr/*out*/)
 {
-    H5B_t		   *new_bt = NULL, *tmp_bt = NULL;
-    herr_t		    ret_value = FAIL;
-    intn		    i, k;
-    size_t		    recsize = 0;
+    H5B_t	*new_bt = NULL, *tmp_bt = NULL;
+    herr_t	ret_value = FAIL;
+    intn	i, k, nleft, nright;
+    size_t	recsize = 0;
 
     FUNC_ENTER(H5B_split, FAIL);
 
@@ -628,6 +632,53 @@ H5B_split(H5F_t *f, const H5B_class_t *type, H5B_t *old_bt,
     recsize = old_bt->sizeof_rkey + H5F_SIZEOF_ADDR(f);
     k = H5B_K(f, type);
 
+#ifdef H5B_DEBUG
+    if (H5DEBUG(B)) {
+	const char *side;
+	if (!H5F_addr_defined(&(old_bt->left)) &&
+	    !H5F_addr_defined(&(old_bt->right))) {
+	    side = "ONLY";
+	} else if (!H5F_addr_defined(&(old_bt->right))) {
+	    side = "RIGHT";
+	} else if (!H5F_addr_defined(&(old_bt->left))) {
+	    side = "LEFT";
+	} else {
+	    side = "MIDDLE";
+	}
+	fprintf(H5DEBUG(B), "H5B_split: %3d {%5.3f,%5.3f,%5.3f} %6s",
+		2*k, split_ratios[0], split_ratios[1], split_ratios[2], side);
+    }
+#endif
+
+    /*
+     * Decide how to split the children of the old node among the old node
+     * and the new node.
+     */
+    if (!H5F_addr_defined(&(old_bt->right))) {
+	nleft = 2 * k * split_ratios[2];	/*right*/
+    } else if (!H5F_addr_defined(&(old_bt->left))) {
+	nleft = 2 * k * split_ratios[0];	/*left*/
+    } else {
+	nleft = 2 * k * split_ratios[1];	/*middle*/
+    }
+
+    /*
+     * Keep the new child in the same node as the child that split.  This can
+     * result in nodes that have an unused child when data is written
+     * sequentially, but it simplifies stuff below.
+     */
+    if (idx<nleft && nleft==2*k) {
+	--nleft;
+    } else if (idx>=nleft && 0==nleft) {
+	nleft++;
+    }
+    nright = 2*k - nleft;
+#ifdef H5B_DEBUG
+    if (H5DEBUG(B)) {
+	fprintf(H5DEBUG(B), " split %3d/%-3d\n", nleft, nright);
+    }
+#endif
+    
     /*
      * Create the new B-tree node.
      */
@@ -645,31 +696,32 @@ H5B_split(H5F_t *f, const H5B_class_t *type, H5B_t *old_bt,
      * Copy data from the old node to the new node.
      */
     HDmemcpy(new_bt->page + H5B_SIZEOF_HDR(f),
-	     old_bt->page + H5B_SIZEOF_HDR(f) + k * recsize,
-	     k * recsize + new_bt->sizeof_rkey);
+	     old_bt->page + H5B_SIZEOF_HDR(f) + nleft * recsize,
+	     nright * recsize + new_bt->sizeof_rkey);
     HDmemcpy(new_bt->native,
-	     old_bt->native + k * type->sizeof_nkey,
-	     (k+1) * type->sizeof_nkey);
+	     old_bt->native + nleft * type->sizeof_nkey,
+	     (nright+1) * type->sizeof_nkey);
 
-    for (i = 0; i <= k; i++) {
+    for (i=0; i<=nright; i++) {
 	/* key */
-	new_bt->key[i].dirty = old_bt->key[k+i].dirty;
-	if (old_bt->key[k+i].nkey) {
+	new_bt->key[i].dirty = old_bt->key[nleft+i].dirty;
+	if (old_bt->key[nleft+i].nkey) {
 	    new_bt->key[i].nkey = new_bt->native + i * type->sizeof_nkey;
 	}
 	/* child */
-	if (i < k) {
-	    new_bt->child[i] = old_bt->child[k+i];
+	if (i < nright) {
+	    new_bt->child[i] = old_bt->child[nleft+i];
 	}
     }
-    new_bt->ndirty = new_bt->nchildren = k;
+    new_bt->ndirty = new_bt->nchildren = nright;
 
     /*
      * Truncate the old node.
      */
     old_bt->dirty = TRUE;
-    old_bt->ndirty = old_bt->nchildren = k;
-
+    old_bt->nchildren = nleft;
+    old_bt->ndirty = MIN(old_bt->ndirty, old_bt->nchildren);
+    
     /*
      * Update sibling pointers.
      */
@@ -782,11 +834,21 @@ H5B_decode_keys(H5F_t *f, H5B_t *bt, intn idx)
  *
  * Modifications:
  *
+ * 	Robb Matzke, 28 Sep 1998
+ *	The optional SPLIT_RATIOS[] indicates what percent of the child
+ *	pointers should go in the left node when a node splits.  There are
+ *	three possibilities and a separate split ratio can be specified for
+ *	each: [0] The node that split is the left-most node at its level of
+ *	the tree, [1] the node that split has left and right siblings, [2]
+ *	the node that split is the right-most node at its level of the tree.
+ *	When a node is an only node at its level then we use the right-most
+ *	rule.  If SPLIT_RATIOS is null then default values are used.
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
 H5B_insert(H5F_t *f, const H5B_class_t *type, const haddr_t *addr,
-	   void *udata)
+	   const double split_ratios[], void *udata)
 {
     /*
      * These are defined this way to satisfy alignment constraints.
@@ -815,9 +877,10 @@ H5B_insert(H5F_t *f, const H5B_class_t *type, const haddr_t *addr,
     assert(type->sizeof_nkey <= sizeof _lt_key);
     assert(addr && H5F_addr_defined(addr));
 
-    if ((my_ins = H5B_insert_helper(f, addr, type, lt_key, &lt_key_changed,
-				    md_key, udata, rt_key, &rt_key_changed,
-				    &child/*out*/ )) < 0 || my_ins < 0) {
+    if ((my_ins = H5B_insert_helper(f, addr, type, split_ratios, lt_key,
+				    &lt_key_changed, md_key, udata, rt_key,
+				    &rt_key_changed, &child/*out*/))<0 ||
+	my_ins<0) {
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL,
 		    "unable to insert key");
     }
@@ -934,14 +997,14 @@ H5B_insert(H5F_t *f, const H5B_class_t *type, const haddr_t *addr,
     buf = H5MM_xfree(buf);
     FUNC_LEAVE(ret_value);
 }
-
+    
 
 /*-------------------------------------------------------------------------
  * Function:	H5B_insert_child
  *
- * Purpose:	Insert a child at the specified address with the
- *		specified left or right key.  The BT argument is a pointer
- *		to a protected B-tree node.
+ * Purpose:	Insert a child to the left or right of child[IDX] depending
+ *		on whether ANCHOR is H5B_INS_LEFT or H5B_INS_RIGHT. The BT
+ *		argument is a pointer to a protected B-tree node.
  *
  * Return:	Success:	SUCCEED
  *
@@ -960,12 +1023,13 @@ H5B_insert_child(H5F_t *f, const H5B_class_t *type, H5B_t *bt,
 		 intn idx, const haddr_t *child, H5B_ins_t anchor,
 		 void *md_key)
 {
-    size_t		    recsize;
-    intn		    i;
+    size_t	recsize;
+    intn	i;
 
     FUNC_ENTER(H5B_insert_child, FAIL);
     assert(bt);
     assert(child);
+    assert(bt->nchildren<2*H5B_K(f, type));
 
     bt->dirty = TRUE;
     recsize = bt->sizeof_rkey + H5F_SIZEOF_ADDR(f);
@@ -974,6 +1038,8 @@ H5B_insert_child(H5F_t *f, const H5B_class_t *type, H5B_t *bt,
 	/*
 	 * The MD_KEY is the left key of the new node.
 	 */
+	idx++;
+	
 	HDmemmove(bt->page + H5B_SIZEOF_HDR(f) + (idx+1) * recsize,
 		  bt->page + H5B_SIZEOF_HDR(f) + idx * recsize,
 		  (bt->nchildren - idx) * recsize + bt->sizeof_rkey);
@@ -1060,20 +1126,30 @@ H5B_insert_child(H5F_t *f, const H5B_class_t *type, H5B_t *bt,
  *
  * Modifications:
  *
+ * 	Robb Matzke, 28 Sep 1998
+ *	The optional SPLIT_RATIOS[] indicates what percent of the child
+ *	pointers should go in the left node when a node splits.  There are
+ *	three possibilities and a separate split ratio can be specified for
+ *	each: [0] The node that split is the left-most node at its level of
+ *	the tree, [1] the node that split has left and right siblings, [2]
+ *	the node that split is the right-most node at its level of the tree.
+ *	When a node is an only node at its level then we use the right-most
+ *	rule.  If SPLIT_RATIOS is null then default values are used.
+ *
  *-------------------------------------------------------------------------
  */
 static H5B_ins_t
 H5B_insert_helper(H5F_t *f, const haddr_t *addr, const H5B_class_t *type,
-		  uint8 *lt_key, hbool_t *lt_key_changed,
-		  uint8 *md_key, void *udata,
+		  const double split_ratios[], uint8 *lt_key,
+		  hbool_t *lt_key_changed, uint8 *md_key, void *udata,
 		  uint8 *rt_key, hbool_t *rt_key_changed,
 		  haddr_t *new_node/*out*/)
 {
-    H5B_t		   *bt = NULL, *twin = NULL, *tmp_bt = NULL;
-    intn		    lt = 0, idx = -1, rt, cmp = -1;
-    haddr_t		    child_addr;
-    H5B_ins_t		    my_ins = H5B_INS_ERROR;
-    H5B_ins_t		    ret_value = H5B_INS_ERROR;
+    H5B_t	*bt = NULL, *twin = NULL, *tmp_bt = NULL;
+    intn	lt = 0, idx = -1, rt, cmp = -1;
+    haddr_t	child_addr;
+    H5B_ins_t	my_ins = H5B_INS_ERROR;
+    H5B_ins_t	ret_value = H5B_INS_ERROR;
 
     FUNC_ENTER(H5B_insert_helper, H5B_INS_ERROR);
 
@@ -1163,7 +1239,7 @@ H5B_insert_helper(H5F_t *f, const haddr_t *addr, const H5B_class_t *type,
 	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR,
 			"unable to decode key");
 	}
-	if ((my_ins = H5B_insert_helper(f, bt->child+idx, type,
+	if ((my_ins = H5B_insert_helper(f, bt->child+idx, type, split_ratios,
 					bt->key[idx].nkey, lt_key_changed,
 					md_key, udata, bt->key[idx+1].nkey,
 					rt_key_changed,
@@ -1219,7 +1295,7 @@ H5B_insert_helper(H5F_t *f, const haddr_t *addr, const H5B_class_t *type,
 	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR,
 			"unable to decode key");
 	}
-	if ((my_ins = H5B_insert_helper(f, bt->child+idx, type,
+	if ((my_ins = H5B_insert_helper(f, bt->child+idx, type, split_ratios,
 					bt->key[idx].nkey, lt_key_changed,
 					md_key, udata, bt->key[idx+1].nkey,
 					rt_key_changed,
@@ -1278,7 +1354,7 @@ H5B_insert_helper(H5F_t *f, const haddr_t *addr, const H5B_class_t *type,
 	 * Follow a branch out of this node to another subtree.
 	 */
 	assert(idx >= 0 && idx < bt->nchildren);
-	if ((my_ins = H5B_insert_helper(f, bt->child + idx, type,
+	if ((my_ins = H5B_insert_helper(f, bt->child+idx, type, split_ratios,
 					bt->key[idx].nkey, lt_key_changed,
 					md_key, udata,
 					bt->key[idx+1].nkey, rt_key_changed,
@@ -1332,27 +1408,24 @@ H5B_insert_helper(H5F_t *f, const haddr_t *addr, const H5B_class_t *type,
 	ret_value = H5B_INS_NOOP;
 
     } else if (H5B_INS_LEFT == my_ins || H5B_INS_RIGHT == my_ins) {
-	/* Make sure IDX is the slot number for the new node. */
-	if (H5B_INS_RIGHT == my_ins)
-	    idx++;
-
 	/*
 	 * If this node is full then split it before inserting the new child.
 	 */
 	if (bt->nchildren == 2 * H5B_K(f, type)) {
-	    if (H5B_split(f, type, bt, addr, udata, new_node /*out */ ) < 0) {
+	    if (H5B_split(f, type, bt, addr, idx, split_ratios, udata,
+			  new_node/*out*/)<0) {
 		HGOTO_ERROR(H5E_BTREE, H5E_CANTSPLIT, H5B_INS_ERROR,
-			    "can't split node");
+			    "unable to split node");
 	    }
 	    if (NULL == (twin = H5AC_protect(f, H5AC_BT, new_node, type,
 					     udata))) {
 		HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, H5B_INS_ERROR,
-			    "can't load B-tree");
+			    "unable to load node");
 	    }
-	    if (idx <= H5B_K(f, type)) {
+	    if (idx<bt->nchildren) {
 		tmp_bt = bt;
 	    } else {
-		idx -= H5B_K(f, type);
+		idx -= bt->nchildren;
 		tmp_bt = twin;
 	    }
 	} else {
@@ -1881,7 +1954,7 @@ static size_t
 H5B_nodesize(H5F_t *f, const H5B_class_t *type,
 	     size_t *total_nkey_size/*out*/, size_t sizeof_rkey)
 {
-    size_t		    size;
+    size_t	size;
 
     FUNC_ENTER(H5B_nodesize, (size_t) 0);
 
@@ -1930,8 +2003,8 @@ herr_t
 H5B_debug(H5F_t *f, const haddr_t *addr, FILE *stream, intn indent,
 	  intn fwidth, const H5B_class_t *type, void *udata)
 {
-    H5B_t		   *bt = NULL;
-    int			    i;
+    H5B_t	*bt = NULL;
+    int		i;
 
     FUNC_ENTER(H5B_debug, FAIL);
 
@@ -2027,10 +2100,10 @@ static herr_t
 H5B_assert(H5F_t *f, const haddr_t *addr, const H5B_class_t *type,
 	   void *udata)
 {
-    H5B_t		   *bt = NULL;
-    intn		    i, ncell, cmp;
-    static int		    ncalls = 0;
-    herr_t		    status;
+    H5B_t	*bt = NULL;
+    intn	i, ncell, cmp;
+    static int	ncalls = 0;
+    herr_t	status;
 
     /* A queue of child data */
     struct child_t {
diff --git a/src/H5Bprivate.h b/src/H5Bprivate.h
index c20135e..fe287b6 100644
--- a/src/H5Bprivate.h
+++ b/src/H5Bprivate.h
@@ -127,7 +127,7 @@ herr_t H5B_create (H5F_t *f, const H5B_class_t *type, void *udata, haddr_t *);
 herr_t H5B_find (H5F_t *f, const H5B_class_t *type, const haddr_t *addr,
 		 void *udata);
 herr_t H5B_insert (H5F_t *f, const H5B_class_t *type, const haddr_t *addr,
-		   void *udata);
+		   const double split_ratios[], void *udata);
 herr_t H5B_remove(H5F_t *f, const H5B_class_t *type, const haddr_t *addr,
 		  void *udata);
 herr_t H5B_iterate (H5F_t *f, const H5B_class_t *type, const haddr_t *addr,
diff --git a/src/H5D.c b/src/H5D.c
index 02beee5..e4c9c2c 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -72,12 +72,19 @@ const H5D_xfer_t	H5D_xfer_dflt = {
     NULL,			/* Type conversion buffer or NULL	*/
     NULL, 			/* Background buffer or NULL		*/
     H5T_BKG_NO,			/* Type of background buffer needed	*/
+    {0.1, 0.5, 0.9},		/* B-tree node splitting ratios		*/
 #ifndef HAVE_PARALLEL
-    1,              /* Cache the hyperslab blocks by default */
-#else /* HAVE_PARALLEL */
-    0,              /* Don't cache the hyperslab blocks by default (for parallel) */
+    1,				/* Cache the hyperslab blocks by default*/
+#else
+    0,				/*
+				 * Don't cache the hyperslab blocks by
+				 * default (for parallel)
+				 */
 #endif /* HAVE_PARALLEL */
-    0,              /* Default to no upper limit on hyperslab block size to cache */
+    0,              		/*
+				 * Default to no upper limit on hyperslab
+				 * block size to cache
+				 */
 #ifdef HAVE_PARALLEL
     H5D_XFER_DFLT,      	/* Independent data transfer      	*/
 #endif
@@ -89,7 +96,7 @@ static hbool_t interface_initialize_g = FALSE;
 static herr_t H5D_init_interface(void);
 static void H5D_term_interface(void);
 #ifdef HAVE_PARALLEL
-static herr_t H5D_allocate (H5D_t *dataset);
+static herr_t H5D_allocate (H5D_t *dataset, const H5D_xfer_t *xfer);
 #endif
 
 
@@ -876,7 +883,8 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
 	 * Also, only the slowest varying dimension of a simple data space
 	 * can be extendible.
 	 */
-	if ((ndims=H5S_get_simple_extent_dims(space, new_dset->layout.dim, max_dim))<0) {
+	if ((ndims=H5S_get_simple_extent_dims(space, new_dset->layout.dim,
+					      max_dim))<0) {
 	    HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL,
 			"unable to initialize contiguous storage");
 	}
@@ -1011,7 +1019,7 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
      */
     if (new_dset->ent.file->shared->access_parms->driver == H5F_LOW_MPIO &&
 	new_dset->layout.type == H5D_CHUNKED){
-	if (H5D_allocate(new_dset)==FAIL){
+	if (H5D_allocate(new_dset, &H5D_xfer_dflt)<0) {
 	    HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL,
 		"fail in file space allocation for chunks");
 	}
@@ -1164,7 +1172,7 @@ H5D_open(H5G_entry_t *loc, const char *name)
     if (dataset->ent.file->shared->access_parms->driver==H5F_LOW_MPIO &&
 	dataset->layout.type == H5D_CHUNKED &&
 	(dataset->ent.file->intent & H5F_ACC_RDWR)){
-	if (H5D_allocate(dataset)==FAIL){
+	if (H5D_allocate(dataset, &H5D_xfer_dflt)<0) {
 	    HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL,
 		"fail in file space allocation dataset");
 	}
@@ -2052,7 +2060,7 @@ H5D_extend (H5D_t *dataset, const hsize_t *size)
 	 */
 	if (dataset->ent.file->shared->access_parms->driver==H5F_LOW_MPIO &&
 	    dataset->layout.type==H5D_CHUNKED){
-	    if (H5D_allocate(dataset)==FAIL){
+	    if (H5D_allocate(dataset, &H5D_xfer_dflt)<0) {
 		HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
 		    "fail in file space allocation for chunks");
 	    }
@@ -2141,10 +2149,10 @@ H5D_typeof (H5D_t *dset)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5D_allocate (H5D_t *dataset)
+H5D_allocate (H5D_t *dataset, const H5D_xfer_t *xfer)
 {
-    H5S_t	*space = NULL;
-    herr_t	ret_value = FAIL;
+    H5S_t		*space = NULL;
+    herr_t		ret_value = FAIL;
     hsize_t		space_dim[H5O_LAYOUT_NDIMS];
     intn		space_ndims;
     H5O_layout_t	*layout;
@@ -2172,7 +2180,8 @@ H5D_allocate (H5D_t *dataset)
 			 "unable to read data space info from dataset header");
 	}
 	/* get current dims of dataset */
-	if ((space_ndims=H5S_get_simple_extent_dims(space, space_dim, NULL)) <= 0 ||
+	if ((space_ndims=H5S_get_simple_extent_dims(space, space_dim,
+						    NULL)) <= 0 ||
 	    space_ndims+1 != layout->ndims){
 	    HRETURN_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
 			"unable to allocate chunk storage");
@@ -2181,9 +2190,9 @@ H5D_allocate (H5D_t *dataset)
 	space_dim[space_ndims] = layout->dim[space_ndims];
 
 	if (H5F_istore_allocate(dataset->ent.file,
-		(layout), space_dim,
-		&(dataset->create_parms->pline))==FAIL){
-		HRETURN(FAIL);
+				(layout), space_dim, xfer->split_ratios,
+				&(dataset->create_parms->pline))<0) {
+	    HRETURN(FAIL);
 	}
 	break;
 
diff --git a/src/H5Distore.c b/src/H5Distore.c
index 31f1ec8..88399fd 100644
--- a/src/H5Distore.c
+++ b/src/H5Distore.c
@@ -68,11 +68,18 @@
 static hbool_t		interface_initialize_g = FALSE;
 #define INTERFACE_INIT NULL
 
+/*
+ * Given a B-tree node return the dimensionality of the chunks pointed to by
+ * that node.
+ */
+#define H5F_ISTORE_NDIMS(X)	((intn)(((X)->sizeof_rkey-8)/8))
+
 /* Raw data chunks are cached.  Each entry in the cache is: */
 typedef struct H5F_rdcc_ent_t {
     hbool_t	locked;		/*entry is locked in cache		*/
     hbool_t	dirty;		/*needs to be written to disk?		*/
     H5O_layout_t *layout;	/*the layout message			*/
+    double	split_ratios[3];/*B-tree node splitting ratios		*/
     H5O_pline_t	*pline;		/*filter pipeline message		*/
     hssize_t	offset[H5O_LAYOUT_NDIMS]; /*chunk name			*/
     size_t	rd_count;	/*bytes remaining to be read		*/
@@ -215,7 +222,7 @@ H5F_istore_decode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
 {
     H5F_istore_key_t	*key = (H5F_istore_key_t *) _key;
     intn		i;
-    intn		ndims = (intn)((bt->sizeof_rkey-8)/4);
+    intn		ndims = H5F_ISTORE_NDIMS(bt);
 
     FUNC_ENTER(H5F_istore_decode_key, FAIL);
 
@@ -224,12 +231,12 @@ H5F_istore_decode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
     assert(bt);
     assert(raw);
     assert(key);
-    assert(ndims > 0 && ndims <= H5O_LAYOUT_NDIMS);
+    assert(ndims>0 && ndims<=H5O_LAYOUT_NDIMS);
 
     /* decode */
     UINT32DECODE(raw, key->nbytes);
     UINT32DECODE(raw, key->filter_mask);
-    for (i = 0; i < ndims; i++) {
+    for (i=0; i<ndims; i++) {
 	UINT64DECODE(raw, key->offset[i]);
     }
 
@@ -250,14 +257,14 @@ H5F_istore_decode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
  *		Friday, October 10, 1997
  *
  * Modifications:
- *
+ *	
  *-------------------------------------------------------------------------
  */
 static herr_t
 H5F_istore_encode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
 {
     H5F_istore_key_t	*key = (H5F_istore_key_t *) _key;
-    intn		ndims = (intn)((bt->sizeof_rkey-8) / 4);
+    intn		ndims = H5F_ISTORE_NDIMS(bt);
     intn		i;
 
     FUNC_ENTER(H5F_istore_encode_key, FAIL);
@@ -267,12 +274,12 @@ H5F_istore_encode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
     assert(bt);
     assert(raw);
     assert(key);
-    assert(ndims > 0 && ndims <= H5O_LAYOUT_NDIMS);
+    assert(ndims>0 && ndims<=H5O_LAYOUT_NDIMS);
 
     /* encode */
     UINT32ENCODE(raw, key->nbytes);
     UINT32ENCODE(raw, key->filter_mask);
-    for (i = 0; i < ndims; i++) {
+    for (i=0; i<ndims; i++) {
 	UINT64ENCODE(raw, key->offset[i]);
     }
 
@@ -826,7 +833,8 @@ H5F_istore_flush_entry (H5F_t *f, H5F_rdcc_ent_t *ent, hbool_t reset)
 	 * Create the chunk it if it doesn't exist, or reallocate the chunk if
 	 * its size changed.  Then write the data into the file.
 	 */
-	if (H5B_insert(f, H5B_ISTORE, &(ent->layout->addr), &udata)<0) {
+	if (H5B_insert(f, H5B_ISTORE, &(ent->layout->addr), ent->split_ratios,
+		       &udata)<0) {
 	    HGOTO_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			 "unable to allocate chunk");
 	}
@@ -1161,8 +1169,9 @@ H5F_istore_prune (H5F_t *f, size_t size)
  */
 static void *
 H5F_istore_lock (H5F_t *f, const H5O_layout_t *layout,
-		 const H5O_pline_t *pline, const hssize_t offset[],
-		 hbool_t relax, intn *idx_hint/*in,out*/)
+		 const double split_ratios[], const H5O_pline_t *pline,
+		 const hssize_t offset[], hbool_t relax,
+		 intn *idx_hint/*in,out*/)
 {
     uintn		idx;			/*hash index number	*/
     hbool_t		found = FALSE;		/*already in cache?	*/
@@ -1177,7 +1186,8 @@ H5F_istore_lock (H5F_t *f, const H5O_layout_t *layout,
     void		*ret_value=NULL;	/*return value		*/
 
     FUNC_ENTER (H5F_istore_lock, NULL);
-
+    assert(split_ratios);
+    
     if (rdcc->nslots>0) {
 	idx = layout->addr.offset;
 	for (i=0; i<layout->ndims; i++) idx = (idx<<1) ^ offset[i];
@@ -1316,6 +1326,9 @@ H5F_istore_lock (H5F_t *f, const H5O_layout_t *layout,
 	ent->rd_count = chunk_size;
 	ent->wr_count = chunk_size;
 	ent->chunk = chunk;
+	ent->split_ratios[0] = split_ratios[0];
+	ent->split_ratios[1] = split_ratios[1];
+	ent->split_ratios[2] = split_ratios[2];
 
 	/* Add it to the cache */
 	assert(NULL==rdcc->slot[idx]);
@@ -1413,6 +1426,7 @@ H5F_istore_lock (H5F_t *f, const H5O_layout_t *layout,
  */
 static herr_t
 H5F_istore_unlock (H5F_t *f, const H5O_layout_t *layout,
+		   const double split_ratios[],
 		   const H5O_pline_t *pline, hbool_t dirty,
 		   const hssize_t offset[], intn *idx_hint,
 		   uint8 *chunk, size_t naccessed)
@@ -1451,6 +1465,9 @@ H5F_istore_unlock (H5F_t *f, const H5O_layout_t *layout,
 	    }
 	    x.alloc_size = x.chunk_size;
 	    x.chunk = chunk;
+	    x.split_ratios[0] = split_ratios[0];
+	    x.split_ratios[1] = split_ratios[1];
+	    x.split_ratios[2] = split_ratios[2];
 	    H5F_istore_flush_entry (f, &x, TRUE);
 	} else {
 	    H5MM_xfree (chunk);
@@ -1492,7 +1509,7 @@ H5F_istore_unlock (H5F_t *f, const H5O_layout_t *layout,
  *-------------------------------------------------------------------------
  */
 herr_t
-H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
+H5F_istore_read(H5F_t *f, const H5D_xfer_t *xfer, const H5O_layout_t *layout,
 		const H5O_pline_t *pline, const hssize_t offset_f[],
 		const hsize_t size[], void *buf)
 {
@@ -1580,6 +1597,7 @@ H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
 	 if (f->shared->access_parms->driver==H5F_LOW_MPIO){
 	    H5F_istore_ud1_t	udata;
 	    H5O_layout_t	l;	/* temporary layout */
+	    H5D_xfer_t		tmp_xfer = *xfer;
 	    if (H5F_istore_get_addr(f, layout, chunk_offset, &udata)==FAIL){
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 				"unable to locate raw data chunk");
@@ -1595,15 +1613,14 @@ H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
 	    for (i=l.ndims; i-- > 0;)
 		l.dim[i] = layout->dim[i];
 	    l.addr = udata.addr;
-	    if (H5F_arr_read(f, &l,
-			    pline, NULL /* no efl */,
-			    sub_size, size_m,
-			    sub_offset_m, offset_wrt_chunk,
-			    H5D_XFER_DFLT, buf)==FAIL){
+	    tmp_xfer.xfer_mode = H5D_XFER_DFLT;
+	    if (H5F_arr_read(f, &tmp_xfer, &l, pline, NULL/*no efl*/,
+			     sub_size, size_m, sub_offset_m, offset_wrt_chunk,
+			     buf)==FAIL){
 		HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
 			     "unable to read raw data from file");
-	    };
-	}else{
+	    }
+	} else {
 #endif
 
 #ifdef AKC
@@ -1613,23 +1630,24 @@ H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
 	    }
 	    printf(")\n");
 #endif
-
-	/*
-	 * Lock the chunk, transfer data to the application, then unlock the
-	 * chunk.
-	 */
-	if (NULL==(chunk=H5F_istore_lock (f, layout, pline, chunk_offset,
-					  FALSE, &idx_hint))) {
-	    HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
-			   "unable to read raw data chunk");
-	}
-	H5V_hyper_copy(layout->ndims, sub_size, size_m, sub_offset_m,
-		       (void*)buf, layout->dim, offset_wrt_chunk, chunk);
-	if (H5F_istore_unlock (f, layout, pline, FALSE, chunk_offset,
-			       &idx_hint, chunk, naccessed)<0) {
-	    HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
-			   "unable to unlock raw data chunk");
-	}
+	    /*
+	     * Lock the chunk, transfer data to the application, then unlock
+	     * the chunk.
+	     */
+	    if (NULL==(chunk=H5F_istore_lock (f, layout, xfer->split_ratios, 
+					      pline, chunk_offset,
+					      FALSE, &idx_hint))) {
+		HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
+			       "unable to read raw data chunk");
+	    }
+	    H5V_hyper_copy(layout->ndims, sub_size, size_m, sub_offset_m,
+			   (void*)buf, layout->dim, offset_wrt_chunk, chunk);
+	    if (H5F_istore_unlock (f, layout, xfer->split_ratios, pline,
+				   FALSE, chunk_offset, &idx_hint, chunk,
+				   naccessed)<0) {
+		HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
+			       "unable to unlock raw data chunk");
+	    }
 #ifdef HAVE_PARALLEL
 	}
 #endif
@@ -1663,7 +1681,7 @@ H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
  *-------------------------------------------------------------------------
  */
 herr_t
-H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
+H5F_istore_write(H5F_t *f, const H5D_xfer_t *xfer, const H5O_layout_t *layout,
 		 const H5O_pline_t *pline, const hssize_t offset_f[],
 		 const hsize_t size[], const void *buf)
 {
@@ -1688,7 +1706,7 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
     assert(layout && H5D_CHUNKED==layout->type);
     assert(layout->ndims>0 && layout->ndims<=H5O_LAYOUT_NDIMS);
     assert(H5F_addr_defined(&(layout->addr)));
-    assert (offset_f);
+    assert(offset_f);
     assert(size);
     assert(buf);
 
@@ -1755,6 +1773,7 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
 	 if (f->shared->access_parms->driver==H5F_LOW_MPIO){
 	    H5F_istore_ud1_t	udata;
 	    H5O_layout_t	l;	/* temporary layout */
+	    H5D_xfer_t		tmp_xfer = *xfer;
 	    if (H5F_istore_get_addr(f, layout, chunk_offset, &udata)==FAIL){
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 				"unable to locate raw data chunk");
@@ -1770,15 +1789,14 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
 	    for (i=l.ndims; i-- > 0;)
 		l.dim[i] = layout->dim[i];
 	    l.addr = udata.addr;
-	    if (H5F_arr_write(f, &l,
-			    pline, NULL /* no efl */,
-			    sub_size, size_m,
-			    sub_offset_m, offset_wrt_chunk,
-			    H5D_XFER_DFLT, buf)==FAIL){
+	    tmp_xfer.xfer_mode = H5D_XFER_DFLT;
+	    if (H5F_arr_write(f, &tmp_xfer, &l, pline, NULL/*no efl*/,
+			      sub_size, size_m, sub_offset_m, offset_wrt_chunk,
+			      buf)==FAIL){
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
-			     "unable to write raw data to file");
-	    };
-	}else{
+			       "unable to write raw data to file");
+	    }
+	} else {
 #endif
 
 #ifdef AKC
@@ -1792,7 +1810,8 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
 	     * Lock the chunk, copy from application to chunk, then unlock the
 	     * chunk.
 	     */
-	    if (NULL==(chunk=H5F_istore_lock (f, layout, pline, chunk_offset,
+	    if (NULL==(chunk=H5F_istore_lock (f, layout, xfer->split_ratios,
+					      pline, chunk_offset,
 					      naccessed==chunk_size,
 					      &idx_hint))) {
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
@@ -1801,8 +1820,9 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
 	    H5V_hyper_copy(layout->ndims, sub_size,
 			   layout->dim, offset_wrt_chunk, chunk,
 			   size_m, sub_offset_m, buf);
-	    if (H5F_istore_unlock (f, layout, pline, TRUE, chunk_offset,
-				   &idx_hint, chunk, naccessed)<0) {
+	    if (H5F_istore_unlock (f, layout, xfer->split_ratios, pline, TRUE,
+				   chunk_offset, &idx_hint, chunk,
+				   naccessed)<0) {
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			       "uanble to unlock raw data chunk");
 	    }
@@ -2047,7 +2067,8 @@ H5F_istore_get_addr (H5F_t *f, const H5O_layout_t *layout,
  */
 herr_t
 H5F_istore_allocate (H5F_t *f, const H5O_layout_t *layout,
-		     const hsize_t *space_dim, const H5O_pline_t *pline)
+		     const hsize_t *space_dim, const double split_ratios[],
+		     const H5O_pline_t *pline)
 {
 
     intn		i, carry;
@@ -2106,13 +2127,15 @@ H5F_istore_allocate (H5F_t *f, const H5O_layout_t *layout,
 	     * Lock the chunk, copy from application to chunk, then unlock the
 	     * chunk.
 	     */
-	    if (NULL==(chunk=H5F_istore_lock (f, layout, pline, chunk_offset,
-					      FALSE, &idx_hint))) {
+	    if (NULL==(chunk=H5F_istore_lock (f, layout, split_ratios, pline,
+					      chunk_offset, FALSE,
+					      &idx_hint))) {
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			       "unable to read raw data chunk");
 	    }
-	    if (H5F_istore_unlock (f, layout, pline, TRUE, chunk_offset,
-				   &idx_hint, chunk, chunk_size)<0) {
+	    if (H5F_istore_unlock (f, layout, split_ratios, pline, TRUE,
+				   chunk_offset, &idx_hint, chunk,
+				   chunk_size)<0) {
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			       "uanble to unlock raw data chunk");
 	    }
diff --git a/src/H5Dprivate.h b/src/H5Dprivate.h
index 5bc6920..c647cf0 100644
--- a/src/H5Dprivate.h
+++ b/src/H5Dprivate.h
@@ -55,8 +55,9 @@ typedef struct H5D_xfer_t {
     void		*tconv_buf;	/*type conversion buffer or null     */
     void		*bkg_buf;	/*background buffer or null	     */
     H5T_bkg_t		need_bkg;	/*type of background buffer needed   */
-    uintn       cache_hyper;    /* Whether to (try to) cache hyperslab blocks during I/O */
-    uintn       block_limit;    /* The largest hyperslab block to try to cache */
+    double		split_ratios[3];/*B-tree node splitting ratios	     */
+    uintn       	cache_hyper;    /*cache hyperslab blocks during I/O? */
+    uintn       	block_limit;    /*largest hyperslab block to cache   */
     H5D_transfer_t	xfer_mode;	/*independent or collective transfer */
 } H5D_xfer_t;
 
diff --git a/src/H5Farray.c b/src/H5Farray.c
index 27ec922..b3ebcff 100644
--- a/src/H5Farray.c
+++ b/src/H5Farray.c
@@ -110,14 +110,19 @@ H5F_arr_create (H5F_t *f, struct H5O_layout_t *layout/*in,out*/)
  *		June 2, 1998	Albert Cheng
  *		Added xfer_mode argument
  *
+ * 		Sep 28, 1998	Robb Matzke
+ *		Added the `xfer' argument and removed the `xfer_mode'
+ *		argument since it's a field of `xfer'.
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5F_arr_read (H5F_t *f, const struct H5O_layout_t *layout,
+H5F_arr_read (H5F_t *f, const H5D_xfer_t *xfer,
+	      const struct H5O_layout_t *layout,
 	      const struct H5O_pline_t *pline, const struct H5O_efl_t *efl,
 	      const hsize_t _hslab_size[], const hsize_t mem_size[],
 	      const hssize_t mem_offset[], const hssize_t file_offset[],
-	      const H5D_transfer_t xfer_mode, void *_buf/*out*/)
+	      void *_buf/*out*/)
 {
     uint8	*buf = (uint8 *)_buf;		/*cast for arithmetic	*/
     hssize_t	file_stride[H5O_LAYOUT_NDIMS];	/*strides through file	*/
@@ -148,7 +153,7 @@ H5F_arr_read (H5F_t *f, const struct H5O_layout_t *layout,
     H5V_vector_cpy (layout->ndims, hslab_size, _hslab_size);
 
 #ifdef HAVE_PARALLEL
-    if (xfer_mode==H5D_XFER_COLLECTIVE){
+    if (xfer->xfer_mode==H5D_XFER_COLLECTIVE){
 	if (layout->type != H5D_CONTIGUOUS)
 	    HRETURN_ERROR (H5E_DATASET, H5E_READERROR, FAIL,
 			   "collective access on non-contiguous datasets not "
@@ -222,7 +227,7 @@ H5F_arr_read (H5F_t *f, const struct H5O_layout_t *layout,
 	 * memory.
 	 */
 #ifdef HAVE_PARALLEL
-	if (xfer_mode==H5D_XFER_COLLECTIVE){
+	if (xfer->xfer_mode==H5D_XFER_COLLECTIVE){
 	    /* Currently supports same number of collective access.
 	     * Need to be changed LATER to combine all reads into one
 	     * collective MPIO call.
@@ -253,7 +258,8 @@ H5F_arr_read (H5F_t *f, const struct H5O_layout_t *layout,
 		    HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
 				   "external data read failed");
 		}
-	    } else if (H5F_block_read (f, &addr, elmt_size, xfer_mode, buf)<0) {
+	    } else if (H5F_block_read (f, &addr, elmt_size, xfer->xfer_mode,
+				       buf)<0) {
 		HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
 			       "block read failed");
 	    }
@@ -286,7 +292,7 @@ H5F_arr_read (H5F_t *f, const struct H5O_layout_t *layout,
 			       "unable to copy into a proper hyperslab");
 	    }
 	}
-	if (H5F_istore_read (f, layout, pline, file_offset, hslab_size,
+	if (H5F_istore_read (f, xfer, layout, pline, file_offset, hslab_size,
 			     buf)<0) {
 	    HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL, "chunked read failed");
 	}
@@ -328,15 +334,19 @@ H5F_arr_read (H5F_t *f, const struct H5O_layout_t *layout,
  *		June 2, 1998	Albert Cheng
  *		Added xfer_mode argument
  *
+ * 		Sep 28, 1998	Robb Matzke
+ *		Added `xfer' argument, removed `xfer_mode' argument since it
+ *		is a member of H5D_xfer_t.
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5F_arr_write (H5F_t *f, const struct H5O_layout_t *layout,
+H5F_arr_write (H5F_t *f, const H5D_xfer_t *xfer,
+	       const struct H5O_layout_t *layout,
 	       const struct H5O_pline_t *pline,
 	       const struct H5O_efl_t *efl, const hsize_t _hslab_size[],
 	       const hsize_t mem_size[], const hssize_t mem_offset[],
-	       const hssize_t file_offset[], const H5D_transfer_t xfer_mode,
-	       const void *_buf)
+	       const hssize_t file_offset[], const void *_buf)
 {
     const uint8	*buf = (const uint8 *)_buf;	/*cast for arithmetic	*/
     hssize_t	file_stride[H5O_LAYOUT_NDIMS];	/*strides through file	*/
@@ -355,35 +365,40 @@ H5F_arr_write (H5F_t *f, const struct H5O_layout_t *layout,
     FUNC_ENTER (H5F_arr_write, FAIL);
 
     /* Check args */
-    assert (f);
-    assert (layout);
-    assert (_hslab_size);
-    assert (file_offset);
-    assert (mem_offset);
-    assert (mem_size);
-    assert (buf);
+    assert(f);
+    assert(layout);
+    assert(_hslab_size);
+    assert(file_offset);
+    assert(mem_offset);
+    assert(mem_size);
+    assert(buf);
 
     /* Make a local copy of _size so we can modify it */
     H5V_vector_cpy (layout->ndims, hslab_size, _hslab_size);
 
 #ifdef HAVE_PARALLEL
-    if (xfer_mode==H5D_XFER_COLLECTIVE){
-	if (layout->type != H5D_CONTIGUOUS)
+    if (xfer->xfer_mode==H5D_XFER_COLLECTIVE) {
+	if (layout->type != H5D_CONTIGUOUS) {
 	    HRETURN_ERROR (H5E_DATASET, H5E_WRITEERROR, FAIL,
-		"collective access on non-contiguous datasets not supported yet");
+			   "collective access on non-contiguous datasets not "
+			   "supported yet");
+	}
     }
 #endif
 #ifdef QAK
-{
-    extern int qak_debug;
-
-    printf("%s: layout->ndims=%d\n",FUNC,(int)layout->ndims);
-    for(i=0; i<layout->ndims; i++)
-        printf("%s: %d: hslab_size=%d, mem_size=%d, mem_offset=%d, file_offset=%d\n",FUNC,i,(int)_hslab_size[i],(int)mem_size[i],(int)mem_offset[i],(int)file_offset[i]);
-    if(qak_debug) {
-        printf("%s: *buf=%d, *(buf+1)=%d\n", FUNC,(int)*(const uint16 *)buf,(int)*((const uint16 *)buf+1));
+    {
+	extern int qak_debug;
+
+	printf("%s: layout->ndims=%d\n",FUNC,(int)layout->ndims);
+	for(i=0; i<layout->ndims; i++)
+	    printf("%s: %d: hslab_size=%d, mem_size=%d, mem_offset=%d, "
+		   "file_offset=%d\n", FUNC, i, (int)_hslab_size[i],
+		   (int)mem_size[i],(int)mem_offset[i],(int)file_offset[i]);
+	if(qak_debug) {
+	    printf("%s: *buf=%d, *(buf+1)=%d\n", FUNC,
+		   (int)*(const uint16 *)buf, (int)*((const uint16 *)buf+1));
+	}
     }
-}
 #endif /* QAK */
 
     switch (layout->type) {
@@ -440,7 +455,7 @@ H5F_arr_write (H5F_t *f, const struct H5O_layout_t *layout,
 	 * disk.
 	 */
 #ifdef HAVE_PARALLEL
-	if (xfer_mode==H5D_XFER_COLLECTIVE){
+	if (xfer->xfer_mode==H5D_XFER_COLLECTIVE){
 	    /* Currently supports same number of collective access.
 	     * Need to be changed LATER to combine all writes into one
 	     * collective MPIO call.
@@ -454,11 +469,13 @@ H5F_arr_write (H5F_t *f, const struct H5O_layout_t *layout,
 	    MPI_Allreduce(&temp, &min, 1, MPI_UNSIGNED_LONG, MPI_MIN,
 		f->shared->access_parms->u.mpio.comm);
 #ifdef AKC
-printf("nelmts=%lu, min=%lu, max=%lu\n", temp, min, max);
+	    printf("nelmts=%lu, min=%lu, max=%lu\n", temp, min, max);
 #endif
-	    if (max != min)
+	    if (max != min) {
 		HRETURN_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL,
-		    "collective access with unequal number of blocks not supported yet");
+			      "collective access with unequal number of "
+			      "blocks not supported yet");
+	    }
 	}
 #endif
 
@@ -470,7 +487,8 @@ printf("nelmts=%lu, min=%lu, max=%lu\n", temp, min, max);
 		    HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
 				   "external data write failed");
 		}
-	    } else if (H5F_block_write (f, &addr, elmt_size, xfer_mode, buf)<0) {
+	    } else if (H5F_block_write(f, &addr, elmt_size, xfer->xfer_mode,
+				       buf)<0) {
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			       "block write failed");
 	    }
@@ -490,7 +508,7 @@ printf("nelmts=%lu, min=%lu, max=%lu\n", temp, min, max);
 
     case H5D_CHUNKED:
 	/*
-	 * This method is unable to access external raw daa files or to copy
+	 * This method is unable to access external raw data files or to copy
 	 * from a proper hyperslab.
 	 */
 	if (efl && efl->nused>0) {
@@ -504,7 +522,7 @@ printf("nelmts=%lu, min=%lu, max=%lu\n", temp, min, max);
 			       "unable to copy from a proper hyperslab");
 	    }
 	}
-	if (H5F_istore_write (f, layout, pline, file_offset, hslab_size,
+	if (H5F_istore_write (f, xfer, layout, pline, file_offset, hslab_size,
 			      buf)<0) {
 	    HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			   "chunked write failed");
diff --git a/src/H5Fistore.c b/src/H5Fistore.c
index 31f1ec8..88399fd 100644
--- a/src/H5Fistore.c
+++ b/src/H5Fistore.c
@@ -68,11 +68,18 @@
 static hbool_t		interface_initialize_g = FALSE;
 #define INTERFACE_INIT NULL
 
+/*
+ * Given a B-tree node return the dimensionality of the chunks pointed to by
+ * that node.
+ */
+#define H5F_ISTORE_NDIMS(X)	((intn)(((X)->sizeof_rkey-8)/8))
+
 /* Raw data chunks are cached.  Each entry in the cache is: */
 typedef struct H5F_rdcc_ent_t {
     hbool_t	locked;		/*entry is locked in cache		*/
     hbool_t	dirty;		/*needs to be written to disk?		*/
     H5O_layout_t *layout;	/*the layout message			*/
+    double	split_ratios[3];/*B-tree node splitting ratios		*/
     H5O_pline_t	*pline;		/*filter pipeline message		*/
     hssize_t	offset[H5O_LAYOUT_NDIMS]; /*chunk name			*/
     size_t	rd_count;	/*bytes remaining to be read		*/
@@ -215,7 +222,7 @@ H5F_istore_decode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
 {
     H5F_istore_key_t	*key = (H5F_istore_key_t *) _key;
     intn		i;
-    intn		ndims = (intn)((bt->sizeof_rkey-8)/4);
+    intn		ndims = H5F_ISTORE_NDIMS(bt);
 
     FUNC_ENTER(H5F_istore_decode_key, FAIL);
 
@@ -224,12 +231,12 @@ H5F_istore_decode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
     assert(bt);
     assert(raw);
     assert(key);
-    assert(ndims > 0 && ndims <= H5O_LAYOUT_NDIMS);
+    assert(ndims>0 && ndims<=H5O_LAYOUT_NDIMS);
 
     /* decode */
     UINT32DECODE(raw, key->nbytes);
     UINT32DECODE(raw, key->filter_mask);
-    for (i = 0; i < ndims; i++) {
+    for (i=0; i<ndims; i++) {
 	UINT64DECODE(raw, key->offset[i]);
     }
 
@@ -250,14 +257,14 @@ H5F_istore_decode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
  *		Friday, October 10, 1997
  *
  * Modifications:
- *
+ *	
  *-------------------------------------------------------------------------
  */
 static herr_t
 H5F_istore_encode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
 {
     H5F_istore_key_t	*key = (H5F_istore_key_t *) _key;
-    intn		ndims = (intn)((bt->sizeof_rkey-8) / 4);
+    intn		ndims = H5F_ISTORE_NDIMS(bt);
     intn		i;
 
     FUNC_ENTER(H5F_istore_encode_key, FAIL);
@@ -267,12 +274,12 @@ H5F_istore_encode_key(H5F_t __unused__ *f, H5B_t *bt, uint8 *raw, void *_key)
     assert(bt);
     assert(raw);
     assert(key);
-    assert(ndims > 0 && ndims <= H5O_LAYOUT_NDIMS);
+    assert(ndims>0 && ndims<=H5O_LAYOUT_NDIMS);
 
     /* encode */
     UINT32ENCODE(raw, key->nbytes);
     UINT32ENCODE(raw, key->filter_mask);
-    for (i = 0; i < ndims; i++) {
+    for (i=0; i<ndims; i++) {
 	UINT64ENCODE(raw, key->offset[i]);
     }
 
@@ -826,7 +833,8 @@ H5F_istore_flush_entry (H5F_t *f, H5F_rdcc_ent_t *ent, hbool_t reset)
 	 * Create the chunk it if it doesn't exist, or reallocate the chunk if
 	 * its size changed.  Then write the data into the file.
 	 */
-	if (H5B_insert(f, H5B_ISTORE, &(ent->layout->addr), &udata)<0) {
+	if (H5B_insert(f, H5B_ISTORE, &(ent->layout->addr), ent->split_ratios,
+		       &udata)<0) {
 	    HGOTO_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			 "unable to allocate chunk");
 	}
@@ -1161,8 +1169,9 @@ H5F_istore_prune (H5F_t *f, size_t size)
  */
 static void *
 H5F_istore_lock (H5F_t *f, const H5O_layout_t *layout,
-		 const H5O_pline_t *pline, const hssize_t offset[],
-		 hbool_t relax, intn *idx_hint/*in,out*/)
+		 const double split_ratios[], const H5O_pline_t *pline,
+		 const hssize_t offset[], hbool_t relax,
+		 intn *idx_hint/*in,out*/)
 {
     uintn		idx;			/*hash index number	*/
     hbool_t		found = FALSE;		/*already in cache?	*/
@@ -1177,7 +1186,8 @@ H5F_istore_lock (H5F_t *f, const H5O_layout_t *layout,
     void		*ret_value=NULL;	/*return value		*/
 
     FUNC_ENTER (H5F_istore_lock, NULL);
-
+    assert(split_ratios);
+    
     if (rdcc->nslots>0) {
 	idx = layout->addr.offset;
 	for (i=0; i<layout->ndims; i++) idx = (idx<<1) ^ offset[i];
@@ -1316,6 +1326,9 @@ H5F_istore_lock (H5F_t *f, const H5O_layout_t *layout,
 	ent->rd_count = chunk_size;
 	ent->wr_count = chunk_size;
 	ent->chunk = chunk;
+	ent->split_ratios[0] = split_ratios[0];
+	ent->split_ratios[1] = split_ratios[1];
+	ent->split_ratios[2] = split_ratios[2];
 
 	/* Add it to the cache */
 	assert(NULL==rdcc->slot[idx]);
@@ -1413,6 +1426,7 @@ H5F_istore_lock (H5F_t *f, const H5O_layout_t *layout,
  */
 static herr_t
 H5F_istore_unlock (H5F_t *f, const H5O_layout_t *layout,
+		   const double split_ratios[],
 		   const H5O_pline_t *pline, hbool_t dirty,
 		   const hssize_t offset[], intn *idx_hint,
 		   uint8 *chunk, size_t naccessed)
@@ -1451,6 +1465,9 @@ H5F_istore_unlock (H5F_t *f, const H5O_layout_t *layout,
 	    }
 	    x.alloc_size = x.chunk_size;
 	    x.chunk = chunk;
+	    x.split_ratios[0] = split_ratios[0];
+	    x.split_ratios[1] = split_ratios[1];
+	    x.split_ratios[2] = split_ratios[2];
 	    H5F_istore_flush_entry (f, &x, TRUE);
 	} else {
 	    H5MM_xfree (chunk);
@@ -1492,7 +1509,7 @@ H5F_istore_unlock (H5F_t *f, const H5O_layout_t *layout,
  *-------------------------------------------------------------------------
  */
 herr_t
-H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
+H5F_istore_read(H5F_t *f, const H5D_xfer_t *xfer, const H5O_layout_t *layout,
 		const H5O_pline_t *pline, const hssize_t offset_f[],
 		const hsize_t size[], void *buf)
 {
@@ -1580,6 +1597,7 @@ H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
 	 if (f->shared->access_parms->driver==H5F_LOW_MPIO){
 	    H5F_istore_ud1_t	udata;
 	    H5O_layout_t	l;	/* temporary layout */
+	    H5D_xfer_t		tmp_xfer = *xfer;
 	    if (H5F_istore_get_addr(f, layout, chunk_offset, &udata)==FAIL){
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 				"unable to locate raw data chunk");
@@ -1595,15 +1613,14 @@ H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
 	    for (i=l.ndims; i-- > 0;)
 		l.dim[i] = layout->dim[i];
 	    l.addr = udata.addr;
-	    if (H5F_arr_read(f, &l,
-			    pline, NULL /* no efl */,
-			    sub_size, size_m,
-			    sub_offset_m, offset_wrt_chunk,
-			    H5D_XFER_DFLT, buf)==FAIL){
+	    tmp_xfer.xfer_mode = H5D_XFER_DFLT;
+	    if (H5F_arr_read(f, &tmp_xfer, &l, pline, NULL/*no efl*/,
+			     sub_size, size_m, sub_offset_m, offset_wrt_chunk,
+			     buf)==FAIL){
 		HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
 			     "unable to read raw data from file");
-	    };
-	}else{
+	    }
+	} else {
 #endif
 
 #ifdef AKC
@@ -1613,23 +1630,24 @@ H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
 	    }
 	    printf(")\n");
 #endif
-
-	/*
-	 * Lock the chunk, transfer data to the application, then unlock the
-	 * chunk.
-	 */
-	if (NULL==(chunk=H5F_istore_lock (f, layout, pline, chunk_offset,
-					  FALSE, &idx_hint))) {
-	    HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
-			   "unable to read raw data chunk");
-	}
-	H5V_hyper_copy(layout->ndims, sub_size, size_m, sub_offset_m,
-		       (void*)buf, layout->dim, offset_wrt_chunk, chunk);
-	if (H5F_istore_unlock (f, layout, pline, FALSE, chunk_offset,
-			       &idx_hint, chunk, naccessed)<0) {
-	    HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
-			   "unable to unlock raw data chunk");
-	}
+	    /*
+	     * Lock the chunk, transfer data to the application, then unlock
+	     * the chunk.
+	     */
+	    if (NULL==(chunk=H5F_istore_lock (f, layout, xfer->split_ratios, 
+					      pline, chunk_offset,
+					      FALSE, &idx_hint))) {
+		HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
+			       "unable to read raw data chunk");
+	    }
+	    H5V_hyper_copy(layout->ndims, sub_size, size_m, sub_offset_m,
+			   (void*)buf, layout->dim, offset_wrt_chunk, chunk);
+	    if (H5F_istore_unlock (f, layout, xfer->split_ratios, pline,
+				   FALSE, chunk_offset, &idx_hint, chunk,
+				   naccessed)<0) {
+		HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL,
+			       "unable to unlock raw data chunk");
+	    }
 #ifdef HAVE_PARALLEL
 	}
 #endif
@@ -1663,7 +1681,7 @@ H5F_istore_read(H5F_t *f, const H5O_layout_t *layout,
  *-------------------------------------------------------------------------
  */
 herr_t
-H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
+H5F_istore_write(H5F_t *f, const H5D_xfer_t *xfer, const H5O_layout_t *layout,
 		 const H5O_pline_t *pline, const hssize_t offset_f[],
 		 const hsize_t size[], const void *buf)
 {
@@ -1688,7 +1706,7 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
     assert(layout && H5D_CHUNKED==layout->type);
     assert(layout->ndims>0 && layout->ndims<=H5O_LAYOUT_NDIMS);
     assert(H5F_addr_defined(&(layout->addr)));
-    assert (offset_f);
+    assert(offset_f);
     assert(size);
     assert(buf);
 
@@ -1755,6 +1773,7 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
 	 if (f->shared->access_parms->driver==H5F_LOW_MPIO){
 	    H5F_istore_ud1_t	udata;
 	    H5O_layout_t	l;	/* temporary layout */
+	    H5D_xfer_t		tmp_xfer = *xfer;
 	    if (H5F_istore_get_addr(f, layout, chunk_offset, &udata)==FAIL){
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 				"unable to locate raw data chunk");
@@ -1770,15 +1789,14 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
 	    for (i=l.ndims; i-- > 0;)
 		l.dim[i] = layout->dim[i];
 	    l.addr = udata.addr;
-	    if (H5F_arr_write(f, &l,
-			    pline, NULL /* no efl */,
-			    sub_size, size_m,
-			    sub_offset_m, offset_wrt_chunk,
-			    H5D_XFER_DFLT, buf)==FAIL){
+	    tmp_xfer.xfer_mode = H5D_XFER_DFLT;
+	    if (H5F_arr_write(f, &tmp_xfer, &l, pline, NULL/*no efl*/,
+			      sub_size, size_m, sub_offset_m, offset_wrt_chunk,
+			      buf)==FAIL){
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
-			     "unable to write raw data to file");
-	    };
-	}else{
+			       "unable to write raw data to file");
+	    }
+	} else {
 #endif
 
 #ifdef AKC
@@ -1792,7 +1810,8 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
 	     * Lock the chunk, copy from application to chunk, then unlock the
 	     * chunk.
 	     */
-	    if (NULL==(chunk=H5F_istore_lock (f, layout, pline, chunk_offset,
+	    if (NULL==(chunk=H5F_istore_lock (f, layout, xfer->split_ratios,
+					      pline, chunk_offset,
 					      naccessed==chunk_size,
 					      &idx_hint))) {
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
@@ -1801,8 +1820,9 @@ H5F_istore_write(H5F_t *f, const H5O_layout_t *layout,
 	    H5V_hyper_copy(layout->ndims, sub_size,
 			   layout->dim, offset_wrt_chunk, chunk,
 			   size_m, sub_offset_m, buf);
-	    if (H5F_istore_unlock (f, layout, pline, TRUE, chunk_offset,
-				   &idx_hint, chunk, naccessed)<0) {
+	    if (H5F_istore_unlock (f, layout, xfer->split_ratios, pline, TRUE,
+				   chunk_offset, &idx_hint, chunk,
+				   naccessed)<0) {
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			       "uanble to unlock raw data chunk");
 	    }
@@ -2047,7 +2067,8 @@ H5F_istore_get_addr (H5F_t *f, const H5O_layout_t *layout,
  */
 herr_t
 H5F_istore_allocate (H5F_t *f, const H5O_layout_t *layout,
-		     const hsize_t *space_dim, const H5O_pline_t *pline)
+		     const hsize_t *space_dim, const double split_ratios[],
+		     const H5O_pline_t *pline)
 {
 
     intn		i, carry;
@@ -2106,13 +2127,15 @@ H5F_istore_allocate (H5F_t *f, const H5O_layout_t *layout,
 	     * Lock the chunk, copy from application to chunk, then unlock the
 	     * chunk.
 	     */
-	    if (NULL==(chunk=H5F_istore_lock (f, layout, pline, chunk_offset,
-					      FALSE, &idx_hint))) {
+	    if (NULL==(chunk=H5F_istore_lock (f, layout, split_ratios, pline,
+					      chunk_offset, FALSE,
+					      &idx_hint))) {
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			       "unable to read raw data chunk");
 	    }
-	    if (H5F_istore_unlock (f, layout, pline, TRUE, chunk_offset,
-				   &idx_hint, chunk, chunk_size)<0) {
+	    if (H5F_istore_unlock (f, layout, split_ratios, pline, TRUE,
+				   chunk_offset, &idx_hint, chunk,
+				   chunk_size)<0) {
 		HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL,
 			       "uanble to unlock raw data chunk");
 	    }
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index a4e47fd..9513689 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -506,6 +506,7 @@ typedef struct H5F_t {
 struct H5O_layout_t;		/*forward decl for prototype arguments */
 struct H5O_efl_t;		/*forward decl for prototype arguments */
 struct H5O_pline_t;		/*forward decl for prototype arguments */
+struct H5D_xfer_t;		/*forward decl for prototype arguments */
 
 /* library variables */
 extern const H5F_create_t H5F_create_dflt;
@@ -529,18 +530,18 @@ herr_t H5F_istore_debug(H5F_t *f, const haddr_t *addr, FILE * stream,
 
 /* Functions that operate on array storage */
 herr_t H5F_arr_create(H5F_t *f, struct H5O_layout_t *layout /*in,out*/);
-herr_t H5F_arr_read (H5F_t *f, const struct H5O_layout_t *layout,
+herr_t H5F_arr_read (H5F_t *f, const struct H5D_xfer_t *xfer,
+		     const struct H5O_layout_t *layout,
 		     const struct H5O_pline_t *pline,
 		     const struct H5O_efl_t *efl, const hsize_t _hslab_size[],
 		     const hsize_t mem_size[], const hssize_t mem_offset[],
-		     const hssize_t file_offset[],
-		     const H5D_transfer_t xfer_mode, void *_buf/*out*/);
-herr_t H5F_arr_write (H5F_t *f, const struct H5O_layout_t *layout,
+		     const hssize_t file_offset[], void *_buf/*out*/);
+herr_t H5F_arr_write (H5F_t *f, const struct H5D_xfer_t *xfer,
+		      const struct H5O_layout_t *layout,
 		      const struct H5O_pline_t *pline,
 		      const struct H5O_efl_t *efl, const hsize_t _hslab_size[],
 		      const hsize_t mem_size[], const hssize_t mem_offset[],
-		      const hssize_t file_offset[],
-		      const H5D_transfer_t xfer_mode, const void *_buf);
+		      const hssize_t file_offset[], const void *_buf);
 
 /* Functions that operate on indexed storage */
 herr_t H5F_istore_init (H5F_t *f);
@@ -548,17 +549,20 @@ herr_t H5F_istore_flush (H5F_t *f, hbool_t preempt);
 herr_t H5F_istore_dest (H5F_t *f);
 herr_t H5F_istore_stats (H5F_t *f, hbool_t headers);
 herr_t H5F_istore_create(H5F_t *f, struct H5O_layout_t *layout /*in,out*/);
-herr_t H5F_istore_read(H5F_t *f, const struct H5O_layout_t *layout,
+herr_t H5F_istore_read(H5F_t *f, const struct H5D_xfer_t *xfer,
+		       const struct H5O_layout_t *layout,
 		       const struct H5O_pline_t *pline,
 		       const hssize_t offset[], const hsize_t size[],
 		       void *buf /*out */ );
-herr_t H5F_istore_write(H5F_t *f, const struct H5O_layout_t *layout,
+herr_t H5F_istore_write(H5F_t *f, const struct H5D_xfer_t *xfer,
+			const struct H5O_layout_t *layout,
 			const struct H5O_pline_t *pline,
 			const hssize_t offset[], const hsize_t size[],
 			const void *buf);
 herr_t H5F_istore_allocate (H5F_t *f,
 			    const struct H5O_layout_t *layout,
 			    const hsize_t *space_dim,
+			    const double split_ratios[], 
 			    const struct H5O_pline_t *pline);
 
 /* Functions that operate on contiguous storage wrt boot block */
diff --git a/src/H5Gstab.c b/src/H5Gstab.c
index e5a5bab..cd71183 100644
--- a/src/H5Gstab.c
+++ b/src/H5Gstab.c
@@ -183,6 +183,7 @@ H5G_stab_insert(H5G_entry_t *grp_ent, const char *name, H5G_entry_t *obj_ent)
 {
     H5O_stab_t		stab;		/*symbol table message		*/
     H5G_bt_ud1_t	udata;		/*data to pass through B-tree	*/
+    static double	split_ratios[3] = {0.1, 0.5, 0.9};
 
     FUNC_ENTER(H5G_stab_insert, FAIL);
 
@@ -202,7 +203,8 @@ H5G_stab_insert(H5G_entry_t *grp_ent, const char *name, H5G_entry_t *obj_ent)
     udata.ent = *obj_ent;
 
     /* insert */
-    if (H5B_insert(grp_ent->file, H5B_SNODE, &(stab.btree_addr), &udata) < 0) {
+    if (H5B_insert(grp_ent->file, H5B_SNODE, &(stab.btree_addr), split_ratios,
+		   &udata) < 0) {
 	HRETURN_ERROR(H5E_SYM, H5E_CANTINSERT, FAIL, "unable to insert entry");
     }
     
diff --git a/src/H5P.c b/src/H5P.c
index c229e0a..eb4faeb 100644
--- a/src/H5P.c
+++ b/src/H5P.c
@@ -2524,6 +2524,103 @@ H5Pset_deflate(hid_t plist_id, unsigned level)
 }
 
 
+/*-------------------------------------------------------------------------
+ * Function:	H5Pget_btree_ratios
+ *
+ * Purpose:	Queries B-tree split ratios.  See H5Pset_btree_ratios().
+ *
+ * Return:	Success:	SUCCEED with split ratios returned through
+ *				the non-null arguments.
+ *
+ *		Failure:	FAIL
+ *
+ * Programmer:	Robb Matzke
+ *              Monday, September 28, 1998
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_btree_ratios(hid_t plist_id, double *left/*out*/, double *middle/*out*/,
+		    double *right/*out*/)
+{
+    H5D_xfer_t		*plist = NULL;
+
+    FUNC_ENTER(H5Pget_btree_ratios, FAIL);
+    H5TRACE4("e","ixxx",plist_id,left,middle,right);
+
+    /* Check arguments */
+    if (H5P_DATASET_XFER!=H5P_get_class(plist_id) ||
+	NULL==(plist=H5I_object(plist_id))) {
+	HRETURN_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL,
+		      "not a dataset transfer property list");
+    }
+
+    /* Get values */
+    if (left) *left = plist->split_ratios[0];
+    if (middle) *middle = plist->split_ratios[1];
+    if (right) *right = plist->split_ratios[2];
+
+    FUNC_LEAVE(SUCCEED);
+}
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Pset_btree_ratios
+ *
+ * Purpose:	Sets B-tree split ratios for a dataset transfer property
+ *		list. The split ratios determine what percent of children go
+ *		in the first node when a node splits.  The LEFT ratio is
+ *		used when the splitting node is the left-most node at its
+ *		level in the tree; the RIGHT ratio is when the splitting node
+ *		is the right-most node at its level; and the MIDDLE ratio for
+ *		all other cases.  A node which is the only node at its level
+ *		in the tree uses the RIGHT ratio when it splits.  All ratios
+ *		are real numbers between 0 and 1, inclusive.
+ *
+ * Return:	Success:	SUCCEED
+ *
+ *		Failure:	FAIL
+ *
+ * Programmer:	Robb Matzke
+ *              Monday, September 28, 1998
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pset_btree_ratios(hid_t plist_id, double left, double middle,
+		    double right)
+{
+    
+    H5D_xfer_t		*plist = NULL;
+
+    FUNC_ENTER(H5Pget_btree_ratios, FAIL);
+    H5TRACE4("e","iddd",plist_id,left,middle,right);
+
+    /* Check arguments */
+    if (H5P_DATASET_XFER!=H5P_get_class(plist_id) ||
+	NULL==(plist=H5I_object(plist_id))) {
+	HRETURN_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL,
+		      "not a dataset transfer property list");
+    }
+    if (left<0.0 || left>1.0 || middle<0.0 || middle>1.0 ||
+	right<0.0 || right>1.0) {
+	HRETURN_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL,
+		      "split ratio must satisfy 0.0<=X<=1.0");
+    }
+    
+    /* Set values */
+    plist->split_ratios[0] = left;
+    plist->split_ratios[1] = middle;
+    plist->split_ratios[2] = right;
+
+    FUNC_LEAVE(SUCCEED);
+}
+
+
 #ifdef HAVE_PARALLEL
 /*-------------------------------------------------------------------------
  * Function:	H5Pset_mpi
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index 123ec41..cc6c4e3 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -108,6 +108,10 @@ herr_t H5Pget_cache (hid_t plist_id, int *mdc_nelmts/*out*/,
 		     double *rdcc_w0);
 herr_t H5Pset_hyper_cache(hid_t plist_id, unsigned cache, unsigned limit);
 herr_t H5Pget_hyper_cache(hid_t plist_id, unsigned *cache, unsigned *limit);
+herr_t H5Pset_btree_ratios(hid_t plist_id, double left, double middle,
+			   double right);
+herr_t H5Pget_btree_ratios(hid_t plist_id, double *left/*out*/,
+			   double *middle/*out*/, double *right/*out*/);
 
 #ifdef HAVE_PARALLEL
 herr_t H5Pset_mpi (hid_t plist_id, MPI_Comm comm, MPI_Info info);
diff --git a/src/H5Sall.c b/src/H5Sall.c
index 71d8181..e3ea157 100644
--- a/src/H5Sall.c
+++ b/src/H5Sall.c
@@ -27,15 +27,13 @@ static size_t H5S_all_fgath (H5F_t *f, const struct H5O_layout_t *layout,
 			     const struct H5O_efl_t *efl, size_t elmt_size,
 			     const H5S_t *file_space,
 			     H5S_sel_iter_t *file_iter, size_t nelmts,
-			     const void *_xfer_parms,
-			     void *buf/*out*/);
+			     const H5D_xfer_t *xfer_parms, void *buf/*out*/);
 static herr_t H5S_all_fscat (H5F_t *f, const struct H5O_layout_t *layout,
 			     const struct H5O_pline_t *pline,
 			     const struct H5O_efl_t *efl, size_t elmt_size,
 			     const H5S_t *file_space,
 			     H5S_sel_iter_t *file_iter, size_t nelmts,
-			     const void *_xfer_parms,
-			     const void *buf);
+			     const H5D_xfer_t *xfer_parms, const void *buf);
 static size_t H5S_all_mgath (const void *_buf, size_t elmt_size,
 			     const H5S_t *mem_space, H5S_sel_iter_t *mem_iter,
 			     size_t nelmts, void *_tconv_buf/*out*/);
@@ -168,12 +166,11 @@ H5S_all_favail (const H5S_t *space, const H5S_sel_iter_t *sel_iter, size_t max)
  */
 static size_t
 H5S_all_fgath (H5F_t *f, const struct H5O_layout_t *layout,
-	       const struct H5O_pline_t *pline, const struct H5O_efl_t *efl,
-	       size_t elmt_size, const H5S_t *file_space,
-	       H5S_sel_iter_t *file_iter, size_t nelmts,
-	       const void *_xfer_parms, void *_buf/*out*/)
+	       const struct H5O_pline_t *pline,
+	       const struct H5O_efl_t *efl, size_t elmt_size,
+	       const H5S_t *file_space, H5S_sel_iter_t *file_iter,
+	       size_t nelmts, const H5D_xfer_t *xfer_parms, void *_buf/*out*/)
 {
-    const H5D_xfer_t *xfer_parms=(const H5D_xfer_t *)_xfer_parms;   /* Coerce the type */
     hssize_t	file_offset[H5O_LAYOUT_NDIMS];	/*offset of slab in file*/
     hsize_t	hsize[H5O_LAYOUT_NDIMS];	/*size of hyperslab	*/
     hssize_t	zero[H5O_LAYOUT_NDIMS];		/*zero			*/
@@ -225,8 +222,8 @@ H5S_all_fgath (H5F_t *f, const struct H5O_layout_t *layout,
     /*
      * Gather from file.
      */
-    if (H5F_arr_read (f, layout, pline, efl, hsize, hsize, zero, file_offset,
-		      xfer_parms->xfer_mode, buf/*out*/)<0) {
+    if (H5F_arr_read (f, xfer_parms, layout, pline, efl, hsize, hsize, zero,
+		      file_offset, buf/*out*/)<0) {
 	HRETURN_ERROR (H5E_DATASPACE, H5E_READERROR, 0, "read error");
     }
 
@@ -262,9 +259,8 @@ H5S_all_fscat (H5F_t *f, const struct H5O_layout_t *layout,
 	       const struct H5O_pline_t *pline, const struct H5O_efl_t *efl,
 	       size_t elmt_size, const H5S_t *file_space,
 	       H5S_sel_iter_t *file_iter, size_t nelmts,
-	       const void *_xfer_parms, const void *_buf)
+	       const H5D_xfer_t *xfer_parms, const void *_buf)
 {
-    const H5D_xfer_t *xfer_parms=(const H5D_xfer_t *)_xfer_parms;   /* Coerce the type */
     hssize_t	file_offset[H5O_LAYOUT_NDIMS];	/*offset of hyperslab	*/
     hsize_t	hsize[H5O_LAYOUT_NDIMS];	/*size of hyperslab	*/
     hssize_t	zero[H5O_LAYOUT_NDIMS];		/*zero vector		*/
@@ -312,8 +308,8 @@ H5S_all_fscat (H5F_t *f, const struct H5O_layout_t *layout,
     /*
      * Scatter to file.
      */
-    if (H5F_arr_write (f, layout, pline, efl, hsize, hsize, zero,
-		       file_offset, xfer_parms->xfer_mode, buf)<0) {
+    if (H5F_arr_write (f, xfer_parms, layout, pline, efl, hsize, hsize, zero,
+		       file_offset, buf)<0) {
         HRETURN_ERROR (H5E_DATASPACE, H5E_WRITEERROR, FAIL, "write error");
     }
 
diff --git a/src/H5Shyper.c b/src/H5Shyper.c
index c67be6b..54ee1bd 100644
--- a/src/H5Shyper.c
+++ b/src/H5Shyper.c
@@ -58,15 +58,13 @@ static size_t H5S_hyper_fgath (H5F_t *f, const struct H5O_layout_t *layout,
 			       const struct H5O_efl_t *efl, size_t elmt_size,
 			       const H5S_t *file_space,
 			       H5S_sel_iter_t *file_iter, size_t nelmts,
-			       const void *_xfer_parms,
-			       void *buf/*out*/);
+			       const H5D_xfer_t *xfer_parms, void *buf/*out*/);
 static herr_t H5S_hyper_fscat (H5F_t *f, const struct H5O_layout_t *layout,
 			       const struct H5O_pline_t *pline,
 			       const struct H5O_efl_t *efl, size_t elmt_size,
 			       const H5S_t *file_space,
 			       H5S_sel_iter_t *file_iter, size_t nelmts,
-			       const void *_xfer_parms,
-			       const void *buf);
+			       const H5D_xfer_t *xfer_parms, const void *buf);
 static size_t H5S_hyper_mgath (const void *_buf, size_t elmt_size,
 			       const H5S_t *mem_space,
 			       H5S_sel_iter_t *mem_iter, size_t nelmts,
@@ -454,10 +452,10 @@ H5S_hyper_block_cache (H5S_hyper_node_t *node, H5S_hyper_fhyper_info_t *fhyper_i
             hsize[i]=(node->end[i]-node->start[i])+1;
         hsize[fhyper_info->space->extent.u.simple.rank]=fhyper_info->elmt_size;
 
-        if (H5F_arr_read (fhyper_info->f, fhyper_info->layout,
-                fhyper_info->pline, fhyper_info->efl,
-                hsize, hsize, zero, file_offset,
-                fhyper_info->xfer_parms->xfer_mode, node->cinfo.block/*out*/)<0)
+        if (H5F_arr_read (fhyper_info->f, fhyper_info->xfer_parms,
+			  fhyper_info->layout, fhyper_info->pline,
+			  fhyper_info->efl, hsize, hsize, zero, file_offset,
+			  node->cinfo.block/*out*/)<0)
             HRETURN_ERROR (H5E_DATASPACE, H5E_READERROR, FAIL, "read error");
     } /* end if */
     else {
@@ -571,10 +569,10 @@ H5S_hyper_block_write (H5S_hyper_node_t *node, H5S_hyper_fhyper_info_t *fhyper_i
             hsize[i]=(node->end[i]-node->start[i])+1;
         hsize[fhyper_info->space->extent.u.simple.rank]=fhyper_info->elmt_size;
 
-        if (H5F_arr_write (fhyper_info->f, fhyper_info->layout,
-                fhyper_info->pline, fhyper_info->efl,
-                hsize, hsize, zero, file_offset,
-                fhyper_info->xfer_parms->xfer_mode, node->cinfo.block/*out*/)<0)
+        if (H5F_arr_write (fhyper_info->f, fhyper_info->xfer_parms,
+			   fhyper_info->layout, fhyper_info->pline,
+			   fhyper_info->efl, hsize, hsize, zero, file_offset,
+			   node->cinfo.block/*out*/)<0)
             HRETURN_ERROR (H5E_DATASPACE, H5E_WRITEERROR, FAIL, "write error");
 
         /* Release the temporary buffer */
@@ -691,13 +689,13 @@ H5S_hyper_fread (intn dim, H5S_hyper_fhyper_info_t *fhyper_info)
                     /*
                      * Gather from file.
                      */
-                    if (H5F_arr_read (fhyper_info->f, fhyper_info->layout,
-                      fhyper_info->pline, fhyper_info->efl,
-                      hsize, hsize, zero, file_offset,
-                      fhyper_info->xfer_parms->xfer_mode,
-                      fhyper_info->dst/*out*/)<0) {
+                    if (H5F_arr_read (fhyper_info->f, fhyper_info->xfer_parms,
+				      fhyper_info->layout, fhyper_info->pline,
+				      fhyper_info->efl, hsize, hsize, zero,
+				      file_offset,
+				      fhyper_info->dst/*out*/)<0) {
                         HRETURN_ERROR (H5E_DATASPACE, H5E_READERROR, 0,
-                       "read error");
+				       "read error");
                     }
 #ifdef QAK
             printf("%s: check 2.3, region #%d\n",FUNC,(int)i);
@@ -793,10 +791,9 @@ H5S_hyper_fgath (H5F_t *f, const struct H5O_layout_t *layout,
 		 const struct H5O_pline_t *pline,
 		 const struct H5O_efl_t *efl, size_t elmt_size,
 		 const H5S_t *file_space, H5S_sel_iter_t *file_iter,
-		 size_t nelmts, const void *_xfer_parms,
+		 size_t nelmts, const H5D_xfer_t *xfer_parms,
 		 void *_buf/*out*/)
 {
-    const H5D_xfer_t *xfer_parms=(const H5D_xfer_t *)_xfer_parms;   /* Coerce the type */
     H5S_hyper_bound_t **lo_bounds;    /* Lower (closest to the origin) bound array for each dimension */
     H5S_hyper_bound_t **hi_bounds;    /* Upper (farthest from the origin) bound array for each dimension */
     H5S_hyper_fhyper_info_t fhyper_info;  /* Block of parameters to pass into recursive calls */
@@ -962,12 +959,12 @@ H5S_hyper_fwrite (intn dim, H5S_hyper_fhyper_info_t *fhyper_info)
                     /*
                      * Scatter to file.
                      */
-                    if (H5F_arr_write (fhyper_info->f, fhyper_info->layout,
-                       fhyper_info->pline, fhyper_info->efl,
-                       hsize, hsize, zero, file_offset,
-                       fhyper_info->xfer_parms->xfer_mode,
-                       fhyper_info->src)<0) {
-                        HRETURN_ERROR (H5E_DATASPACE, H5E_WRITEERROR, 0, "write error");
+                    if (H5F_arr_write (fhyper_info->f, fhyper_info->xfer_parms,
+				       fhyper_info->layout, fhyper_info->pline,
+				       fhyper_info->efl, hsize, hsize, zero,
+				       file_offset, fhyper_info->src)<0) {
+                        HRETURN_ERROR (H5E_DATASPACE, H5E_WRITEERROR, 0,
+				       "write error");
                     }
                 } /* end else */
 
@@ -1054,10 +1051,9 @@ H5S_hyper_fscat (H5F_t *f, const struct H5O_layout_t *layout,
 		 const struct H5O_pline_t *pline,
 		 const struct H5O_efl_t *efl, size_t elmt_size,
 		 const H5S_t *file_space, H5S_sel_iter_t *file_iter,
-		 size_t nelmts, const void *_xfer_parms,
+		 size_t nelmts, const H5D_xfer_t *xfer_parms,
 		 const void *_buf)
 {
-    const H5D_xfer_t *xfer_parms=(const H5D_xfer_t *)_xfer_parms;   /* Coerce the type */
     H5S_hyper_bound_t **lo_bounds;    /* Lower (closest to the origin) bound array for each dimension */
     H5S_hyper_bound_t **hi_bounds;    /* Upper (farthest from the origin) bound array for each dimension */
     H5S_hyper_fhyper_info_t fhyper_info;  /* Block of parameters to pass into recursive calls */
diff --git a/src/H5Spoint.c b/src/H5Spoint.c
index f3edd63..d532fcf 100644
--- a/src/H5Spoint.c
+++ b/src/H5Spoint.c
@@ -28,14 +28,14 @@ static size_t H5S_point_fgath (H5F_t *f, const struct H5O_layout_t *layout,
 			       const struct H5O_efl_t *efl, size_t elmt_size,
 			       const H5S_t *file_space,
 			       H5S_sel_iter_t *file_iter, size_t nelmts,
-			       const void *_xfer_parms,
+			       const H5D_xfer_t *xfer_parms,
 			       void *buf/*out*/);
 static herr_t H5S_point_fscat (H5F_t *f, const struct H5O_layout_t *layout,
 			       const struct H5O_pline_t *pline,
 			       const struct H5O_efl_t *efl, size_t elmt_size,
 			       const H5S_t *file_space,
 			       H5S_sel_iter_t *file_iter, size_t nelmts,
-			       const void *_xfer_parms,
+			       const H5D_xfer_t *xfer_parms,
 			       const void *buf);
 static size_t H5S_point_mgath (const void *_buf, size_t elmt_size,
 			       const H5S_t *mem_space,
@@ -267,10 +267,9 @@ H5S_point_fgath (H5F_t *f, const struct H5O_layout_t *layout,
 		 const struct H5O_pline_t *pline,
 		 const struct H5O_efl_t *efl, size_t elmt_size,
 		 const H5S_t *file_space, H5S_sel_iter_t *file_iter,
-		 size_t nelmts, const void *_xfer_parms,
+		 size_t nelmts, const H5D_xfer_t *xfer_parms,
 		 void *_buf/*out*/)
 {
-    const H5D_xfer_t *xfer_parms=(const H5D_xfer_t *)_xfer_parms;   /* Coerce the type */
     hssize_t	file_offset[H5O_LAYOUT_NDIMS];	/*offset of slab in file*/
     hsize_t	hsize[H5O_LAYOUT_NDIMS];	/*size of hyperslab	*/
     hssize_t	zero[H5O_LAYOUT_NDIMS];		/*zero			*/
@@ -318,8 +317,8 @@ H5S_point_fgath (H5F_t *f, const struct H5O_layout_t *layout,
                 file_offset[i] += file_space->select.offset[i];
 
             /* Go read the point */
-            if (H5F_arr_read (f, layout, pline, efl, hsize, hsize, zero,
-			      file_offset, xfer_parms->xfer_mode, buf/*out*/)<0) {
+            if (H5F_arr_read (f, xfer_parms, layout, pline, efl, hsize, hsize,
+			      zero, file_offset, buf/*out*/)<0) {
                 HRETURN_ERROR (H5E_DATASPACE, H5E_READERROR, 0, "read error");
             }
 
@@ -377,10 +376,9 @@ H5S_point_fscat (H5F_t *f, const struct H5O_layout_t *layout,
 		 const struct H5O_pline_t *pline,
 		 const struct H5O_efl_t *efl, size_t elmt_size,
 		 const H5S_t *file_space, H5S_sel_iter_t *file_iter,
-		 size_t nelmts, const void *_xfer_parms,
+		 size_t nelmts, const H5D_xfer_t *xfer_parms,
 		 const void *_buf)
 {
-    const H5D_xfer_t *xfer_parms=(const H5D_xfer_t *)_xfer_parms;   /* Coerce the type */
     hssize_t	file_offset[H5O_LAYOUT_NDIMS];	/*offset of hyperslab	*/
     hsize_t	hsize[H5O_LAYOUT_NDIMS];	/*size of hyperslab	*/
     hssize_t	zero[H5O_LAYOUT_NDIMS];		/*zero vector		*/
@@ -447,8 +445,8 @@ H5S_point_fscat (H5F_t *f, const struct H5O_layout_t *layout,
 	}
 #endif /* QAK */
         /* Go write the point */
-        if (H5F_arr_write (f, layout, pline, efl, hsize, hsize, zero,
-			   file_offset, xfer_parms->xfer_mode, buf)<0) {
+        if (H5F_arr_write (f, xfer_parms, layout, pline, efl, hsize, hsize,
+			   zero, file_offset, buf)<0) {
             HRETURN_ERROR (H5E_DATASPACE, H5E_WRITEERROR, 0, "write error");
         }
 
diff --git a/src/H5Sprivate.h b/src/H5Sprivate.h
index 7d3b93b..c870a29 100644
--- a/src/H5Sprivate.h
+++ b/src/H5Sprivate.h
@@ -20,6 +20,7 @@
 
 /* Private headers needed by this file */
 #include <H5private.h>
+#include <H5Fprivate.h>
 #include <H5Gprivate.h>		/*for H5G_entry_t			     */
 #include <H5Oprivate.h>
 
@@ -192,7 +193,7 @@ typedef struct H5S_fconv_t {
 		   const struct H5O_pline_t *pline,
 		   const struct H5O_efl_t *efl, size_t elmt_size,
 		   const H5S_t *file_space, H5S_sel_iter_t *file_iter,
-		   size_t nelmts, const void *xfer_parms,
+		   size_t nelmts, const struct H5D_xfer_t *xfer_parms,
 		   void *tconv_buf/*out*/);
 
     /* Scatter elements from type conversion buffer to disk */
@@ -200,7 +201,7 @@ typedef struct H5S_fconv_t {
 		   const struct H5O_pline_t *pline,
 		   const struct H5O_efl_t *efl, size_t elmt_size,
 		   const H5S_t *file_space, H5S_sel_iter_t *file_iter,
-		   size_t nelmts, const void *xfer_parms,
+		   size_t nelmts, const struct H5D_xfer_t *xfer_parms,
 		   const void *tconv_buf);
 } H5S_fconv_t;