en-US/vcenter-maintenance-mode.xml

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<section id="vcenter-maintenance-mode">
    <title>vCenter and Maintenance Mode</title>
    <para>To enter maintenance mode on a vCenter host, both vCenter and &PRODUCT; must be used in concert. &PRODUCT; and vCenter have separate maintenance modes that work closely together.</para>
    <orderedlist>
        <listitem><para>Place the host into &PRODUCT;'s "scheduled maintenance" mode. This does not invoke the vCenter maintenance mode, but only causes VMs to be migrated off the host</para>
        <para>When the &PRODUCT; maintenance mode is requested, the host first moves into the Prepare for Maintenance state. In this state it cannot be the target of new guest VM starts. Then all VMs will be migrated off the server.  Live migration will be used to move VMs off the host. This allows the guests to be migrated to other hosts with no disruption to the guests. After this migration is completed, the host will enter the Ready for Maintenance mode.</para></listitem>
        <listitem><para>Wait for the "Ready for Maintenance" indicator to appear in the UI.</para></listitem>
        <listitem><para>Now use vCenter to perform whatever actions are necessary to maintain the host. During this time, the host cannot be the target of new VM allocations.</para></listitem>
        <listitem><para>When the maintenance tasks are complete, take the host out of maintenance mode as follows:</para>
        <orderedlist numeration="loweralpha">
            <listitem><para>First use vCenter to exit the vCenter maintenance mode.</para>
            <para>This makes the host ready for &PRODUCT; to reactivate it.</para></listitem>
            <listitem><para>Then use &PRODUCT;'s administrator UI to cancel the &PRODUCT; maintenance mode</para>
           <para>When the host comes back online, the VMs that were migrated off of it may be migrated back to it manually and new VMs can be added.</para></listitem>
          </orderedlist></listitem>        
       </orderedlist>
    
</section>