anchor.diff:  Only the primary can accept writes from the client, and the primary will always contain the latest changes.
   Since all writes still have to go through the primary region, the writes are not highly-available (meaning they might block for some time if the region becomes unavailable).
   
  -The writes are asynchronously sent to the secondary region replicas using an _Async WAL replication_ feature.
  -This works similarly to HBase's multi-datacenter replication, but instead the data from a region is replicated to the secondary regions.
  -Each secondary replica always receives and observes the writes in the same order that the primary region committed them.
  -This ensures that the secondaries won't diverge from the primary regions data, but since the log replication is asnyc, the data might be stale in secondary regions.
  -In some sense, this design can be thought of as _in-cluster replication_, where instead of replicating to a different datacenter, the data goes to a secondary region to keep secondary region's in-memory state up to date.
  -The data files are shared between the primary region and the other replicas, so that there is no extra storage overhead.
  -However, the secondary regions will have recent non-flushed data in their MemStores, which increases the memory overhead.
  -
  -
  -Async WAL replication feature is being implemented in Phase 2 of issue HBASE-10070.
  -Before this, region replicas will only be updated with flushed data files from the primary (see `hbase.regionserver.storefile.refresh.period` below). It is also possible to use this without setting `storefile.refresh.period` for read only tables.
  -
   
   === Timeline Consistency
   
  
positive.code: ResultScanner scanner = table.getScanner(scan);
  ----
  
  You can inspect whether the results are coming from primary region or not by calling the Result.isStale() method:
  
  [source,java]
  ----
  
negative.code: [source,xml]
  ----
  <property>
      <name>hbase.ipc.client.specificThreadForWriting</name>
      <value>true</value>
      <description>
        Whether to enable interruption of RPC threads at the client side. This is required for region replicas with fallback RPC’s to secondary regions.
      </description>
  </property>
  <property>
    <name>hbase.client.primaryCallTimeout.get</name>
  