title: How does Multiple shards per module support works in ODL nitrogen
body: <p>The module-shards.conf file mentions the following :</p>
  
  <blockquote>
    <p>For Helium we support only one shard per module. Beyond Helium we will support more than 1</p>
  </blockquote>
  
  <p>Have ODL Nitrogen and trying to use "module-shards.conf" like the following :</p>
  
  <pre><code>module-shards = [
      {
          name = "default"
          shards = [
              {
                  name="default1"
                  replicas = [
                      "member-1"
                  ]
              },
              {
                  name="default2"
                  replicas = [
                      "member-1"
                  ]
              }
          ]
      }
  ]
  </code></pre>
  
  <p>That seems to be working as karaf shows the 2 shards successfully created 
  for the same module "default". But how the data is distributed among 
  the 2 shards is not clear, can application control/decide which data goes in which of the module shards.</p>
  
  <p>I am not clear how the application config tree data and the operational tree 
  data for a given module be stored under different shards for the same module.
  If there are multiple shards for the same module, can application decide/control
  which shard to use for storing a particular type of data. For example, 
  can application decide to store the config tree in "default1" shard 
  and operational tree in "default2" shard for the same module "default" ?</p>
  
  <p>Is it possible to disable operational tree component for one of the shards of 
  a given module, say disable operational tree component for shard "default2" 
  of module "default" with 2 shards namely "default1" and "default2" ?</p>