<section>
 <h1 class="contains-headerlink leafygreen-ui-41fr9s" weight="medium">
  Add Shards to a Cluster
  <a class="headerlink leafygreen-ui-1kepx47" href="#add-shards-to-a-cluster" title="Permalink to this heading">
   <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
    <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
    </path>
    <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
    </path>
   </svg>
   <div class="css-1btu0w3 evvkmar0" id="add-shards-to-a-cluster">
   </div>
  </a>
 </h1>
 <div class="leafygreen-ui-a5yxub">
  <p class="css-1cmx2d4 ef7gu8j0">
   On this page
  </p>
  <ul class="css-1qb0mst ef7gu8j1">
   <li class="leafygreen-ui-1e7a0ei">
    <a class="lg-ui-0001 leafygreen-ui-e98ikf" href="#considerations" target="_self">
     <span>
      Considerations
     </span>
    </a>
   </li>
   <li class="leafygreen-ui-1jqtqlb">
    <a class="lg-ui-0001 leafygreen-ui-cpmeq5" href="#add-a-shard-to-a-cluster" target="_self">
     <span>
      Add a Shard to a Cluster
     </span>
    </a>
   </li>
  </ul>
 </div>
 <p class="leafygreen-ui-1kp3ins">
  You add shards to a
  <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/glossary/#std-term-sharded-cluster">
   sharded cluster
  </a>
  after you create the cluster
or any time that you need to add capacity to the cluster. If you have not
created a sharded cluster, see
  <a class="leafygreen-ui-tqgtui" href="/docs/manual/tutorial/deploy-shard-cluster/#std-label-sharding-procedure-setup">
   Deploy a Self-Managed Sharded Cluster
   <!-- -->
   .
  </a>
 </p>
 <p class="leafygreen-ui-1kp3ins">
  All shards must be
  <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/glossary/#std-term-replica-set">
   replica sets
   <!-- -->
   .
  </a>
 </p>
 <section>
  <h2 class="contains-headerlink leafygreen-ui-19f71ei" weight="medium">
   Considerations
   <a class="headerlink leafygreen-ui-1kepx47" href="#considerations" title="Permalink to this heading">
    <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
     <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
     </path>
     <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
     </path>
    </svg>
    <div class="css-1btu0w3 evvkmar0" id="considerations">
    </div>
   </a>
  </h2>
  <section>
   <h3 class="contains-headerlink leafygreen-ui-15ajumo" weight="medium">
    Balancing
    <a class="headerlink leafygreen-ui-1kepx47" href="#balancing" title="Permalink to this heading">
     <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
      <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
      </path>
      <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
      </path>
     </svg>
     <div class="css-1btu0w3 evvkmar0" id="balancing">
     </div>
    </a>
   </h3>
   <p class="leafygreen-ui-1kp3ins">
    When you add a shard to a sharded cluster, you affect the balance of
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/glossary/#std-term-chunk">
     chunks
    </a>
    among the shards of a cluster for all existing sharded
collections. The balancer will begin migrating chunks so that the
cluster will achieve balance. See
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/core/sharding-balancer-administration/#std-label-sharding-internals-balancing">
     Balancer Internals
    </a>
    for
more information.
   </p>
  </section>
  <section>
   <h3 class="contains-headerlink leafygreen-ui-15ajumo" weight="medium">
    Capacity Planning
    <a class="headerlink leafygreen-ui-1kepx47" href="#capacity-planning" title="Permalink to this heading">
     <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
      <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
      </path>
      <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
      </path>
     </svg>
     <div class="css-1btu0w3 evvkmar0" id="capacity-planning">
     </div>
    </a>
   </h3>
   <p class="leafygreen-ui-1kp3ins">
    When adding a shard to a cluster, always ensure that the cluster has
enough capacity to support the migration required for balancing the
cluster without affecting legitimate production traffic.
   </p>
  </section>
  <section>
   <h3 class="contains-headerlink leafygreen-ui-15ajumo" weight="medium">
    DDL Operations
    <a class="headerlink leafygreen-ui-1kepx47" href="#ddl-operations" title="Permalink to this heading">
     <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
      <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
      </path>
      <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
      </path>
     </svg>
     <div class="css-1btu0w3 evvkmar0" id="ddl-operations">
     </div>
    </a>
   </h3>
   <p class="leafygreen-ui-1kp3ins">
    If you add a shard while your cluster executes a DDL operation
(operation that modifies a collection such as
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/command/reshardCollection/#mongodb-dbcommand-dbcmd.reshardCollection">
     <code class="leafygreen-ui-1l06pbn">
      reshardCollection
     </code>
    </a>
    ), the operation that adds a shard only
executes after the concurrent DDL operation finishes.
   </p>
  </section>
 </section>
 <section>
  <h2 class="contains-headerlink leafygreen-ui-19f71ei" weight="medium">
   Add a Shard to a Cluster
   <a class="headerlink leafygreen-ui-1kepx47" href="#add-a-shard-to-a-cluster" title="Permalink to this heading">
    <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
     <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
     </path>
     <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
     </path>
    </svg>
    <div class="css-1btu0w3 evvkmar0" id="add-a-shard-to-a-cluster">
    </div>
   </a>
  </h2>
  <p class="leafygreen-ui-1kp3ins">
   You interact with a sharded cluster by connecting to a
   <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/program/mongos/#mongodb-binary-bin.mongos">
    <code class="leafygreen-ui-1l06pbn">
     mongos
    </code>
   </a>
   instance.
  </p>
  <ol class="leafygreen-ui-rioki0" type="1">
   <li class="leafygreen-ui-d7p7b6">
    <p class="leafygreen-ui-1kp3ins">
     In
     <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="https://www.mongodb.com/docs/mongodb-shell/#mongodb-binary-bin.mongosh" target="_self">
      <span>
       <code class="leafygreen-ui-1l06pbn">
        mongosh
       </code>
      </span>
     </a>
     , connect to the
     <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/program/mongos/#mongodb-binary-bin.mongos">
      <code class="leafygreen-ui-1l06pbn">
       mongos
      </code>
     </a>
     instance. For example, if a
     <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/program/mongos/#mongodb-binary-bin.mongos">
      <code class="leafygreen-ui-1l06pbn">
       mongos
      </code>
     </a>
     is accessible at
     <code class="leafygreen-ui-1l06pbn">
      mongos0.example.net
     </code>
     on port
     <code class="leafygreen-ui-1l06pbn">
      27017
     </code>
     , issue the following
command:
    </p>
    <script class="structured_data" type="application/ld+json">
     {"@context":"https://schema.org","@type":"SoftwareSourceCode","codeSampleType":"code snippet","text":"mongosh --host mongos0.example.net --port 27017","programmingLanguage":"Bash"}
    </script>
    <div class="css-16lmvu9">
     <div class="leafygreen-ui-196mwvg">
      <div class="leafygreen-ui-yzcs8i">
       <pre class="leafygreen-ui-1q4bxgx" tabindex="-1"><code class="lg-highlight-hljs-light bash leafygreen-ui-9ybzas"><table class="leafygreen-ui-1tr4g10"><tbody><tr class=""><td class="leafygreen-ui-7razhx">mongosh --host mongos0.example.net --port 27017</td></tr></tbody></table></code></pre>
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           </path>
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         </div>
        </button>
       </div>
      </div>
     </div>
    </div>
   </li>
   <li class="leafygreen-ui-d7p7b6">
    <p class="leafygreen-ui-1kp3ins">
     Add a shard replica set to the cluster using the
     <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/method/sh.addShard/#mongodb-method-sh.addShard">
      <code class="leafygreen-ui-1l06pbn">
       sh.addShard()
      </code>
     </a>
     method, as shown in the example below. Issue
     <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/method/sh.addShard/#mongodb-method-sh.addShard">
      <code class="leafygreen-ui-1l06pbn">
       sh.addShard()
      </code>
     </a>
     separately for each shard. Specify the name of the replica set and a
member of the set.
    </p>
    <div class="leafygreen-ui-15mdk4" role="note">
     <h2 class="leafygreen-ui-6n7b7d">
      Note
     </h2>
     <h3 class="leafygreen-ui-144d5kf">
      <strong>
       Optional
      </strong>
     </h3>
     <div class="leafygreen-ui-9mycqc">
      <p class="leafygreen-ui-1kp3ins">
       You can instead use the
       <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/command/addShard/#mongodb-dbcommand-dbcmd.addShard">
        <code class="leafygreen-ui-1l06pbn">
         addShard
        </code>
       </a>
       database
command, which lets you specify a name and maximum size for the
shard. If you do not specify these, MongoDB automatically assigns
a name and maximum size. To use the database command, see
       <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/command/addShard/#mongodb-dbcommand-dbcmd.addShard">
        <code class="leafygreen-ui-1l06pbn">
         addShard
        </code>
        .
       </a>
      </p>
     </div>
    </div>
    <p class="leafygreen-ui-1kp3ins">
     The following example illustrates adding a shard with
     <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/method/sh.addShard/#mongodb-method-sh.addShard">
      <code class="leafygreen-ui-1l06pbn">
       sh.addShard()
      </code>
      :
     </a>
    </p>
    <p class="leafygreen-ui-1kp3ins">
     To add a shard replica set named
     <code class="leafygreen-ui-1l06pbn">
      rs1
     </code>
     with a member
running on port
     <code class="leafygreen-ui-1l06pbn">
      27018
     </code>
     on
     <code class="leafygreen-ui-1l06pbn">
      mongodb0.example.net
     </code>
     , issue the
following command:
    </p>
    <script class="structured_data" type="application/ld+json">
     {"@context":"https://schema.org","@type":"SoftwareSourceCode","codeSampleType":"code snippet","text":"sh.addShard( \"rs1/mongodb0.example.net:27018\" )","programmingLanguage":"JavaScript"}
    </script>
    <div class="css-16lmvu9">
     <div class="leafygreen-ui-196mwvg">
      <div class="leafygreen-ui-yzcs8i">
       <pre class="leafygreen-ui-1q4bxgx" tabindex="-1"><code class="lg-highlight-hljs-light javascript leafygreen-ui-9ybzas"><table class="leafygreen-ui-1tr4g10"><tbody><tr class=""><td class="leafygreen-ui-7razhx">sh.<span class="lg-highlight-title lg-highlight-function">addShard</span>( <span class="lg-highlight-string">"rs1/mongodb0.example.net:27018"</span> )</td></tr></tbody></table></code></pre>
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           </path>
          </svg>
         </div>
        </button>
       </div>
      </div>
     </div>
    </div>
    <div class="leafygreen-ui-15mdk4" role="note">
     <h2 class="leafygreen-ui-6n7b7d">
      Note
     </h2>
     <div class="leafygreen-ui-9mycqc">
      <p class="leafygreen-ui-1kp3ins">
       It might take some time for
       <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/glossary/#std-term-chunk">
        chunks
       </a>
       to
migrate to the new shard.
      </p>
     </div>
    </div>
   </li>
  </ol>
 </section>
</section>
