docs/en-US/volume-deletion-garbage-collection.xml

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<section id="volume-deletion-garbage-collection">
    <title>Volume Deletion and Garbage Collection</title>
    <para>The deletion of a volume does not delete the snapshots that have been created from the volume</para>
    <para>When a VM is destroyed, data disk volumes that are attached to the VM are not deleted.</para>
    <para>Volumes are permanently destroyed using a garbage collection process.  The global configuration variables expunge.delay and expunge.interval determine when the physical deletion of volumes will occur.</para>
    <itemizedlist>
        <listitem><para>expunge.delay: determines how old the volume must be before it is destroyed, in seconds</para></listitem>
        <listitem><para>expunge.interval: determines how often to run the garbage collection check</para></listitem>
    </itemizedlist>
    <para>Administrators should adjust these values depending on site policies around data retention.</para>
</section>