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@@ -292,6 +292,9 @@ document.write("Last Published: " + document.lastModified);
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<li>
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<a href="#Unsafe+Options">Unsafe Options</a>
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</li>
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+<li>
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+<a href="#Communication+using+the+Netty+framework">Communication using the Netty framework</a>
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+</li>
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</ul>
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</li>
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<li>
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@@ -1105,7 +1108,7 @@ server.3=zoo3:2888:3888</pre>
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<dt>
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-<term>clientPortBindAddress</term>
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+<term>clientPortAddress</term>
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</dt>
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<dd>
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<p>
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@@ -1280,10 +1283,29 @@ server.3=zoo3:2888:3888</pre>
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</p>
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</dd>
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+
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+
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+<dt>
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+<term>cnxTimeout</term>
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+</dt>
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+<dd>
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+<p>(Java system property: zookeeper.<strong>cnxTimeout</strong>)</p>
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+<p>Sets the timeout value for opening connections for leader election notifications.
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+ Only applicable if you are using electionAlg 3.
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+ </p>
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+<div class="note">
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+<div class="label">Note</div>
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+<div class="content">
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+
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+<p>Default value is 5 seconds.</p>
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+
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+</div>
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+</div>
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+</dd>
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</dl>
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<p></p>
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-<a name="N103EC"></a><a name="sc_authOptions"></a>
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+<a name="N103FD"></a><a name="sc_authOptions"></a>
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<h4>Authentication & Authorization Options</h4>
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<p>The options in this section allow control over
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authentication/authorization performed by the service.</p>
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@@ -1317,7 +1339,7 @@ server.3=zoo3:2888:3888</pre>
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</dd>
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</dl>
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-<a name="N1040F"></a><a name="Unsafe+Options"></a>
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+<a name="N10420"></a><a name="Unsafe+Options"></a>
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<h4>Unsafe Options</h4>
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<p>The following options can be useful, but be careful when you use
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them. The risk of each is explained along with the explanation of what
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@@ -1362,7 +1384,40 @@ server.3=zoo3:2888:3888</pre>
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</dd>
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</dl>
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-<a name="N10441"></a><a name="sc_zkCommands"></a>
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+<a name="N10451"></a><a name="Communication+using+the+Netty+framework"></a>
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+<h4>Communication using the Netty framework</h4>
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+<p>
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+<strong>New in
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+ 3.4:</strong> <a href="http://jboss.org/netty">Netty</a>
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+ is an NIO based client/server communication framework, it
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+ simplifies (over NIO being used directly) many of the
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+ complexities of network level communication for java
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+ applications. Additionally the Netty framework has built
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+ in support for encryption (SSL) and authentication
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+ (certificates). These are optional features and can be
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+ turned on or off individually.
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+ </p>
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+<p>Prior to version 3.4 ZooKeeper has always used NIO
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+ directly, however in versions 3.4 and later Netty is
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+ supported as an option to NIO (replaces). NIO continues to
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+ be the default, however Netty based communication can be
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+ used in place of NIO by setting the environment variable
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+ "zookeeper.serverCnxnFactory" to
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+ "org.apache.zookeeper.server.NettyServerCnxnFactory". You
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+ have the option of setting this on either the client(s) or
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+ server(s), typically you would want to set this on both,
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+ however that is at your discretion.
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+ </p>
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+<p>
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+ TBD - tuning options for netty - currently there are none that are netty specific but we should add some. Esp around max bound on the number of reader worker threads netty creates.
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+ </p>
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+<p>
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+ TBD - how to manage encryption
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+ </p>
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+<p>
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+ TBD - how to manage certificates
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+ </p>
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+<a name="N1046E"></a><a name="sc_zkCommands"></a>
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<h3 class="h4">ZooKeeper Commands: The Four Letter Words</h3>
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<p>ZooKeeper responds to a small set of commands. Each command is
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composed of four letters. You issue the commands to ZooKeeper via telnet
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@@ -1500,6 +1555,42 @@ server.3=zoo3:2888:3888</pre>
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operation may be expensive (ie impact server performance),
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use it carefully.</p>
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</dd>
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+
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+
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+
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+<dt>
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+<term>mntr</term>
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+</dt>
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+<dd>
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+<p>
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+<strong>New in 3.4.0:</strong> Outputs a list
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+ of variables that could be used for monitoring the health of the cluster.</p>
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+<pre class="code">$ echo mntr | nc localhost 2185
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+
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+zk_version 3.4.0
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+zk_avg_latency 0
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+zk_max_latency 0
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+zk_min_latency 0
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+zk_packets_received 70
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+zk_packets_sent 69
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+zk_outstanding_requests 0
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+zk_server_state leader
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+zk_znode_count 4
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+zk_watch_count 0
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+zk_ephemerals_count 0
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+zk_approximate_data_size 27
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+zk_followers 4 - only exposed by the Leader
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+zk_synced_followers 4 - only exposed by the Leader
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+zk_pending_syncs 0 - only exposed by the Leader
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+zk_open_file_descriptor_count 23 - only available on Unix platforms
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+zk_max_file_descriptor_count 1024 - only available on Unix platforms
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+</pre>
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+<p>The output is compatible with java properties format and the content
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+ may change over time (new keys added). Your scripts should expect changes.</p>
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+<p>ATTENTION: Some of the keys are platform specific and some of the keys are only exported by the Leader. </p>
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+<p>The output contains multiple lines with the following format:</p>
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+<pre class="code">key \t value</pre>
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+</dd>
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</dl>
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<p>Here's an example of the <strong>ruok</strong>
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@@ -1507,7 +1598,7 @@ server.3=zoo3:2888:3888</pre>
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<pre class="code">$ echo ruok | nc 127.0.0.1 5111
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imok
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</pre>
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-<a name="N104BE"></a><a name="sc_dataFileManagement"></a>
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+<a name="N104FE"></a><a name="sc_dataFileManagement"></a>
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<h3 class="h4">Data File Management</h3>
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<p>ZooKeeper stores its data in a data directory and its transaction
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log in a transaction log directory. By default these two directories are
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@@ -1515,7 +1606,7 @@ imok
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transaction log files in a separate directory than the data files.
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Throughput increases and latency decreases when transaction logs reside
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on a dedicated log devices.</p>
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-<a name="N104C7"></a><a name="The+Data+Directory"></a>
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+<a name="N10507"></a><a name="The+Data+Directory"></a>
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<h4>The Data Directory</h4>
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<p>This directory has two files in it:</p>
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<ul>
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@@ -1561,14 +1652,14 @@ imok
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idempotent nature of its updates. By replaying the transaction log
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against fuzzy snapshots ZooKeeper gets the state of the system at the
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end of the log.</p>
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-<a name="N10503"></a><a name="The+Log+Directory"></a>
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+<a name="N10543"></a><a name="The+Log+Directory"></a>
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<h4>The Log Directory</h4>
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<p>The Log Directory contains the ZooKeeper transaction logs.
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Before any update takes place, ZooKeeper ensures that the transaction
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that represents the update is written to non-volatile storage. A new
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log file is started each time a snapshot is begun. The log file's
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suffix is the first zxid written to that log.</p>
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-<a name="N1050D"></a><a name="sc_filemanagement"></a>
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+<a name="N1054D"></a><a name="sc_filemanagement"></a>
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<h4>File Management</h4>
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<p>The format of snapshot and log files does not change between
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standalone ZooKeeper servers and different configurations of
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@@ -1588,7 +1679,7 @@ imok
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this document for more details on setting a retention policy
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and maintenance of ZooKeeper storage.
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</p>
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-<a name="N10522"></a><a name="sc_commonProblems"></a>
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+<a name="N10562"></a><a name="sc_commonProblems"></a>
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<h3 class="h4">Things to Avoid</h3>
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<p>Here are some common problems you can avoid by configuring
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ZooKeeper correctly:</p>
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@@ -1642,7 +1733,7 @@ imok
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</dd>
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</dl>
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-<a name="N10546"></a><a name="sc_bestPractices"></a>
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+<a name="N10586"></a><a name="sc_bestPractices"></a>
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<h3 class="h4">Best Practices</h3>
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<p>For best results, take note of the following list of good
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Zookeeper practices:</p>
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Flavio Paiva Junqueira
