| 1 | <?xml version="1.0" encoding="UTF-8"?>
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| 2 | <!DOCTYPE topic
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| 3 | PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
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| 4 | <topic xml:lang="en-us" id="snapshots-take-restore-delete">
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| 5 | <title>Taking, Restoring, and Deleting Snapshots</title>
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| 6 |
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| 7 | <body>
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| 8 | <p>There are three operations related to snapshots, as follows: </p>
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| 9 | <ol>
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| 10 | <li>
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| 11 | <p><b outputclass="bold">Take a snapshot.</b> This makes a copy of the machine's current state,
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| 12 | to which you can go back at any given time later. </p>
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| 13 | <ul>
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| 14 | <li>
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| 15 | <p>If your VM is running: </p>
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| 16 | <p>Select <b outputclass="bold">Take Snapshot</b> from the <b outputclass="bold"
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| 17 | >Machine</b> menu in the VM window. </p>
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| 18 | <p>The VM is paused while the snapshot is being created. After snapshot creation, the VM
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| 19 | continues to run as normal. </p>
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| 20 | </li>
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| 21 | <li>
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| 22 | <p>If your VM is in either the Saved or the Powered Off state, as displayed next to the VM
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| 23 | name in the machine list: </p>
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| 24 | <p>Display the Snapshots window and do one of the following: </p>
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| 25 | <ul>
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| 26 | <li>
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| 27 | <p>Click <b outputclass="bold">Take</b> in the Snapshots window toolbar. </p>
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| 28 | </li>
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| 29 | <li>
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| 30 | <p>Right-click the <b outputclass="bold">Current State</b> item in the list and
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| 31 | select <b outputclass="bold">Take</b>. </p>
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| 32 | </li>
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| 33 | </ul>
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| 34 | </li>
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| 35 | </ul>
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| 36 | <p>A dialog is displayed, prompting you for a snapshot name. This name is purely for reference
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| 37 | purposes, to help you remember the state of the snapshot. For example, a useful name would be <i>Fresh
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| 38 | installation from scratch, no Guest Additions</i>, or <i>Service Pack 3 just installed</i>. You can also add
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| 39 | a longer text description in the <b outputclass="bold">Snapshot Description</b> field. </p>
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| 40 | <p>Your new snapshot will then appear in the snapshots list. Underneath your new snapshot, you
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| 41 | will see an item called <b outputclass="bold">Current State</b>, signifying that the current state of your VM
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| 42 | is a variation based on the snapshot you took earlier. If you later take another snapshot, you will see that
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| 43 | they are displayed in sequence, and that each subsequent snapshot is derived from an earlier one. </p>
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| 44 | <fig id="fig-snapshots-list">
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| 45 | <title>Snapshots List For a Virtual Machine</title>
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| 46 | <xref href="images/snapshots-2.png" format="png" platform="htmlhelp">
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| 47 | <image href="images/snapshots-2.png" width="10cm" placement="break">
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| 48 | <alt>Snapshots List For a Virtual Machine</alt>
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| 49 | </image>
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| 50 | </xref>
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| 51 | <image platform="ohc" href="images/snapshots-2.png" width="10cm" placement="break">
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| 52 | <alt>Snapshots List For a Virtual Machine</alt>
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| 53 | </image>
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| 54 | </fig>
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| 55 | <p><ph conkeyref="vbox-conkeyref-phrases/product-name"/> imposes no limits on the number of
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| 56 | snapshots you can take. The only practical limitation is disk space on your host. Each snapshot stores the
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| 57 | state of the virtual machine and thus occupies some disk space. See <xref
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| 58 | href="snapshots-contents.dita#snapshots-contents"/> for details on what is stored in a snapshot. </p>
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| 59 | </li>
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| 60 | <li>
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| 61 | <p><b outputclass="bold">Restore a snapshot.</b> In the Snapshots window, select the snapshot
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| 62 | you have taken and click <b outputclass="bold">Restore</b> in the toolbar. By restoring a snapshot, you go
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| 63 | back or forward in time. The current state of the machine is lost, and the machine is restored to the exact
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| 64 | state it was in when the snapshot was taken. </p>
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| 65 | <note>
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| 66 | <p>Restoring a snapshot will affect the virtual hard drives that are connected to your VM, as
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| 67 | the entire state of the virtual hard drive will be reverted as well. This means also that all files that
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| 68 | have been created since the snapshot and all other file changes <i>will be lost. </i>In order to prevent
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| 69 | such data loss while still making use of the snapshot feature, it is possible to add a second hard drive in
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| 70 | <i>write-through</i> mode using the <userinput>VBoxManage</userinput> interface and use it to store your
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| 71 | data. As write-through hard drives are <i>not</i> included in snapshots, they remain unaltered when a
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| 72 | machine is reverted. See <xref href="hdimagewrites.dita#hdimagewrites"/>. </p>
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| 73 | </note>
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| 74 | <p>To avoid losing the current state when restoring a snapshot, you can create a new snapshot
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| 75 | before the restore operation. </p>
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| 76 | <p>By restoring an earlier snapshot and taking more snapshots from there, it is even possible to
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| 77 | create a kind of alternate reality and to switch between these different histories of the virtual machine.
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| 78 | This can result in a whole tree of virtual machine snapshots. </p>
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| 79 | </li>
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| 80 | <li>
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| 81 | <p><b outputclass="bold">Delete a snapshot.</b> This does not affect the state of the virtual
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| 82 | machine, but only releases the files on disk that <ph conkeyref="vbox-conkeyref-phrases/product-name"/> used
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| 83 | to store the snapshot data, thus freeing disk space. To delete a snapshot, select the snapshot name in the
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| 84 | Snapshots window and click <b outputclass="bold">Delete</b> in the toolbar. Snapshots can be deleted even
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| 85 | while a machine is running. </p>
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| 86 | <note>
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| 87 | <p>Whereas taking and restoring snapshots are fairly quick operations, deleting a snapshot
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| 88 | can take a considerable amount of time since large amounts of data may need to be copied between several
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| 89 | disk image files. Temporary disk files may also need large amounts of disk space while the operation is in
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| 90 | progress. </p>
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| 91 | </note>
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| 92 | <p>There are some situations which cannot be handled while a VM is running, and you will get an
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| 93 | appropriate message that you need to perform this snapshot deletion when the VM is shut down. </p>
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| 94 | </li>
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| 95 | </ol>
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| 96 | </body>
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| 97 |
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| 98 | </topic>
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