doc-exports/docs/dws/umn/dws_01_7115.html

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<h1 class="topictitle1">CNs</h1>
<div id="body8662426"><div class="section" id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_section1201157202712"><h4 class="sectiontitle">Purpose</h4><p id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_p349716118295">After a cluster is created, the number of required CNs varies with service requirements. The CN management function enables you to adjust the number of CNs in the cluster. The operations are as follows:</p>
<ul id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_ul4301511125312"><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li6301911165318"><a href="#EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_section941730165216">Adding CNs</a></li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li130121165315"><a href="#EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_section7292342175210">Deleting CNs</a><div class="note" id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_note536104317508"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_p14361144320503">This feature is supported only in cluster version 8.1.1 or later.</p>
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<div class="section" id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_section881310350358"><h4 class="sectiontitle">Constraints and Limitations</h4><ul id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_ul205441726101618"><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li18544172671615">During resource provisioning, the default number of CNs is 3. You can adjust the number of CNs based on the number of provisioned nodes. The number of CNs ranges from 2 to 20.</li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li16544142691613">Do not perform other O&amp;M operations when adding or deleting a CN.</li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li95447266163">Stop services when adding or deleting a CN.</li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li122591019498">If a fault occurs when you add or delete a CN and the rollback also fails, log in to the background to rectify the fault. For details, see .</li></ul>
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<div class="section" id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_section941730165216"><a name="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_section941730165216"></a><a name="en-us_topic_0000001083058054_section941730165216"></a><h4 class="sectiontitle">Adding CNs</h4><ol id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_o4d27c72c9c5b483283c532fd703af879"><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_l3bf4b8bc45d343b6aec0b48be7dfc1aa"><span>Log in to the GaussDB(DWS) management console.</span></li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li11952509114244"><span>On the <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b95201634184417">Clusters</strong> page, locate the cluster to which you want to add CNs.</span></li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li111926412577"><span>In the <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b63551737155618">Operation </strong>column of the specified cluster, choose <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b107741026155612">More</strong> &gt; <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b106386293560">Manage CN</strong> &gt; <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b17620153135610">Add CN Node</strong>.</span><p><p id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_p1465262712571"></p>
<p id="EN-US_TOPIC_0000001134400786__p1752120514329"><span><img id="EN-US_TOPIC_0000001134400786__image84941526320" src="figure/en-us_image_0000001432579569.png" width="456.855" height="122.494995" title="Click to enlarge" class="imgResize"></span></p>
</p></li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li197211073417"><span>On the displayed page, set the number of CNs as required and click <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b34439542471">OK</strong>.</span><p><p id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_p1313130207"><span><img id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_image133121010019" src="figure/en-us_image_0000001180440335.png" width="354.1125" height="174.870794" title="Click to enlarge" class="imgResize"></span></p>
<div class="notice" id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_note1566711158019"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><ul id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_ul1914809151015"><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li15148390108">Before adding a CN, ensure that the cluster is in the <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b2778259113614">Available</strong>, <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b889561193716">Unbalanced</strong>, or <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b82948517378">Redistributing</strong> state.</li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li3148297103">The number of CNs after adjustment must be greater than the number of deployed CNs, less than or equal to the number of nodes, and less than or equal to 20.</li></ul>
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<div class="section" id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_section7292342175210"><a name="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_section7292342175210"></a><a name="en-us_topic_0000001083058054_section7292342175210"></a><h4 class="sectiontitle">Deleting CNs</h4><ol id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_ol964820365020"><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li76481436905"><span>Log in to the GaussDB(DWS) management console.</span></li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li146498361107"><span>On the <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b83355355528">Clusters</strong> page, locate the cluster from which you want to delete CNs.</span></li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li146491361002"><span>In the <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b20530101311532">Operation</strong> column of the specified cluster, choose <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b95643184536">More </strong>&gt; <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b129152255531">Manage CN</strong> &gt; <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b73611426114411">Delete CN Node</strong>.</span><p><p id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_p364911364017"></p>
<p id="EN-US_TOPIC_0000001134400786__p2941142818384"><span><img id="EN-US_TOPIC_0000001134400786__image4120143114382" src="figure/en-us_image_0000001382420930.png" width="451.8675" height="127.68798000000001" title="Click to enlarge" class="imgResize"></span></p>
</p></li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li09294475117"><span>On the displayed page, select the CN to be deleted and click <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b1961115813379">OK</strong>.</span><p><p id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_p568704518510"><span><img id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_image26875455510" src="figure/en-us_image_0000001134400964.png" height="208.07251500000004" width="410.161094" title="Click to enlarge" class="imgResize"></span></p>
<div class="notice" id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_note104825321674"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><ul id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_ul671217384127"><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li173718426298">At least one CN must be reserved when you delete a CN.</li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li167131638141215">When you delete a CN, the cluster must be in the <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b19927423144116">Available</strong>, <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b119730257414">Degraded</strong>, or <strong id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_b91531129124114">Unbalanced</strong> state.</li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li07134387125">If an elastic IP address has been bound to a CN, the CN cannot be deleted.</li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li197131138101211">If abnormal nodes exist, only the abnormal CNs can be deleted.<ul id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_ul3728111114719"><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li7198164974713">If one CN is faulty, only this CN can be deleted.</li><li id="EN-US_TOPIC_0000001134400786__en-us_topic_0000001083058054_li18671201614482">If two or more CNs are faulty, no CN can be deleted.</li></ul>
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_01_0161.html">Cluster HA</a></div>
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