MINOR: Add note about num.standby.replicas
Reviewers: Guozhang Wang
<span id="streams-developer-guide-standby-replicas"></span><h4><a class="toc-backref" href="#id10">num.standby.replicas</a><a class="headerlink" href="#num-standby-replicas" title="Permalink to this headline"></a></h4>
<blockquote>
<div>The number of standby replicas. Standby replicas are shadow copies of local state stores. Kafka Streams attempts to create the
- specified number of replicas and keep them up to date as long as there are enough instances running.
+ specified number of replicas per store and keep them up to date as long as there are enough instances running.
Standby replicas are used to minimize the latency of task failover. A task that was previously running on a failed instance is
preferred to restart on an instance that has standby replicas so that the local state store restoration process from its
changelog can be minimized. Details about how Kafka Streams makes use of the standby replicas to minimize the cost of
resuming tasks on failover can be found in the <a class="reference internal" href="../architecture.html#streams_architecture_state"><span class="std std-ref">State</span></a> section.</div></blockquote>
</div>
+ <div class="admonition note">
+ <p class="first admonition-title">Note</p>
+ <p class="last">If you enable <cite>n</cite> standby tasks, you need to provision <cite>n+1</cite> <code class="docutils literal"><span class="pre">KafkaStreams</span></code>
+ instances.</p>
+ </div>
<div class="section" id="num-stream-threads">
<h4><a class="toc-backref" href="#id11">num.stream.threads</a><a class="headerlink" href="#num-stream-threads" title="Permalink to this headline"></a></h4>
<blockquote>
