anchor.diff:  |shard2replica2Source |to |shard2replica2Target
   |===
   
  -* Start the ZooKeeper on the Target (DR) side.
  -* Start the SolrCloud on the Target (DR) side.
  -* Start the ZooKeeper on the Source side.
  -* Start the SolrCloud on the Source side. As a general rule, the Target (DR) side of the SolrCloud should be started before the Source side.
  -* Activate the CDCR on Source instance using the CDCR API:
  +* Start ZooKeeper on the Target (DR).
  +* Start SolrCloud on the Target (DR).
  +* Start ZooKeeper on the Source.
  +* Start SolrCloud on the Source. As a general rule, the Target (DR) should be started before the Source.
  +* Activate CDCR on Source instance using the CDCR API:
   +
   [source,text]
   http://host:port/solr/<collection_name>/cdcr?action=START
   +
   There is no need to run the `/cdcr?action=START` command on the Target.
   * Disable the buffer on the Target and Source:
  ++
  +[source,text]
  +http://host:port/solr/collection_name/cdcr?action=DISABLEBUFFER
  ++
  +* Re-enable indexing.
  +
  +=== Bi-Directional Approach
  +
  +[TIP]
  +====
  +When using the bi-directional approach, it is highly recommended to enable CDCR on both cluster-collections before any indexing has taken place.
  +====
  +
  +Based on the same example from uni-directional solution, let's walk through the necessary steps:
  +
  +* Before you begin, stop or pause any indexing processes. This is best done during a small maintenance window.
  +* Stop the SolrCloud instances in both Cluster 1 and Cluster 2.
  +* Upload the modified `solrconfig.xml` to ZooKeeper on both Cluster 1 and Cluster 2 as appropriate, see the examples above in the section <<Bi-Directional Updates>>.
  +* If documents were indexed prior to this exercise, sync the index directories from the Cluster 1 collection to the Cluster 2 collection to the corresponding shard nodes or vice versa. The `rsync` utility works well for this if it's available on your server. Check to be sure the the updated index is copied across.
  ++
  +For example, if there are 2 shards on collection 'cluster1' (the updated collection) with 2 replicas for each shard, copy the corresponding index directories from:
  ++
  +[width="75%",cols="45,10,45"]
  +|===
  +|shard1replica1cluster1 |to |shard1replica1cluster2
  +|shard1replica2cluster1 |to |shard1replica2cluster2
  +|shard2replica1cluster1 |to |shard2replica1cluster2
  +|shard2replica2cluster1 |to |shard2replica2cluster2
  +|===
  +
  +* Start ZooKeeper on Cluster 1.
  +* Start ZooKeeper on Cluster 2.
  +* Start SolrCloud on Cluster 1.
  +* Start SolrCloud on Cluster 2.
  +* If not present, create respective collections in both Cluster 1 and Cluster 2.
  +* Activate the CDCR on Cluster 1 and Cluster 2 instance using the CDCR API:
  ++
  +[source,text]
  +http://host:port/solr/<collection_name>/cdcr?action=START
  ++
  +* Disable the buffer on Cluster 1 and Cluster 2:
   +
   [source,text]
   http://host:port/solr/collection_name/cdcr?action=DISABLEBUFFER
  
positive.code: * Upload the modified `solrconfig.xml` to ZooKeeper on both Source and Target as appropriate, see the examples above.
  * Sync the index directories from the Source collection to Target collection across to the corresponding shard nodes. `rsync` works well for this.
  +
  For example, if there are 2 shards on collection1 with 2 replicas for each shard, copy the corresponding index directories from:
  +
  [width="75%",cols="45,10,45"]
  |===
  
negative.code: 
  == Initial Startup
  
  === Uni-Directional Approach
  
  This is a general approach for initializing CDCR in a production environment. It's based upon an approach taken by the initial working installation of CDCR and generously contributed to illustrate a "real world" scenario.
  
  * CDCR is used to keep a remote disaster-recovery instance available for production backup.
  * This example as 26 clouds with 200 million assets per cloud (15GB indexes). Total document count is over 4.8 billion.
  ** Source and Target clouds were synched in 2-3 hour maintenance windows to establish the base index for the Targets.
  
  As usual, it is good to start small. Sync a single cloud and monitor for a period of time before doing the others. You may need to adjust your settings several times before finding the right balance.
  