doc: Added x-ref links.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>

diff --git a/doc/rados/operations/data-placement.rst b/doc/rados/operations/data-placement.rst
index 0474ffb94ffa18b726b6bf331e4a7af22bfd0d6a..ff128960dc4099506ae81ab36eaad72566018a47 100644 (file)
--- a/doc/rados/operations/data-placement.rst
+++ b/doc/rados/operations/data-placement.rst
@@ -11,24 +11,30 @@ placement planning.  The main data placement planning concepts in Ceph include:
   objects. Pools manage the number of placement groups, the number of replicas,
   and the ruleset for the pool. To store data in a pool, you must have
   an authenticated user with permissions for the pool. Ceph can snapshot pools. 
-  Future versions of Ceph will support namespaces within pools.
+  Future versions of Ceph will support namespaces within pools. See `Pools`_
+  for additional details.
   
 - **Placement Groups:** Ceph maps objects to placement groups (PGs). 
   Placement groups (PGs) are shards or fragments of a logical object pool
   that place objects as a group into OSDs. Placement groups reduce the amount 
   of per-object metadata when Ceph stores the data in OSDs. A larger number of 
-  placement groups (e.g., 100 per OSD) leads to better balancing.
+  placement groups (e.g., 100 per OSD) leads to better balancing. See 
+  `Placement Groups`_ for additional details.
 
 - **CRUSH Maps:**  CRUSH is a big part of what allows Ceph to scale without 
   performance bottlenecks, without limitations to scalability, and without a 
   single point of failure. CRUSH maps provide the physical topology of the 
   cluster to the CRUSH algorithm to determine where the data for an object 
   and its replicas should be stored, and how to do so across failure domains 
-  for added  data safety among other things.
+  for added data safety among other things. See `CRUSH Maps`_ for additional
+  details.
   
 When you initially set up a test cluster, you can use the default values. Once
 you begin planning for a large Ceph cluster, refer to pools, placement groups
 and CRUSH for data placement operations. If you find some aspects challenging,
 `Inktank`_ provides excellent  premium support for Ceph.
 
+.. _Pools: ../pools
+.. _Placement Groups: ../placement-groups
+.. _CRUSH Maps: ../crush-map
 .. _Inktank: http://www.inktank.com
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