Difference between revisions of "stoney conductor: VM Backup"

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#* Save the state of VM <code>vm-001</code> to the file <code>vm-001.state</code>: <syntaxhighlight lang="bash">virsh save vm-001 vm-001.stat</syntaxhighlight>
 
#* Save the state of VM <code>vm-001</code> to the file <code>vm-001.state</code>: <syntaxhighlight lang="bash">virsh save vm-001 vm-001.stat</syntaxhighlight>
 
#* After this command, the VMs CPU and memory state is represented by the file <code>vm-001.state</code> and the VM <code>vm-001</code> is shut down.
 
#* After this command, the VMs CPU and memory state is represented by the file <code>vm-001.state</code> and the VM <code>vm-001</code> is shut down.
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#* Move the disk image <code>/path/to/images/vm-001.qcow2</code> to the retain location: <syntaxhighlight lang="bash">mv /path/to/images/vm-001.qcow2 /path/to/retain/vm-001.qcow2</syntaxhighlight>
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# Move the disk image <code>/path/to/images/vm-001.qcow2</code> to the retain location: <syntaxhighlight lang="bash">mv /path/to/images/vm-001.qcow2 /path/to/retain/vm-001.qcow2</syntaxhighlight>
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#** '''Please note:''' The retain directory (<code>/path/to/retain/</code>) '''has to be''' on the same partition as the images directory (<code>/path/to/images/</code>). This will make the <code>mv</code> operation very fast (only renaming the inode). So the downtime (remember the VM <code>vm-001</code> is shut down) is as short as possible.  
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#* '''Please note:''' The retain directory (<code>/path/to/retain/</code>) '''has to be''' on the same partition as the images directory (<code>/path/to/images/</code>). This will make the <code>mv</code> operation very fast (only renaming the inode). So the downtime (remember the VM <code>vm-001</code> is shut down) is as short as possible.  
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#* Create the new disk image with the old as backing file: <code>qemu-img create -f qcow2 -b my-vm-backup.qcow2 my-vm.qcow2</code>
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# Create the new (empty) disk image with the old as backing store file: <code>qemu-img create -f qcow2 -b my-vm-backup.qcow2 my-vm.qcow2</code>
 
#* Set correct ownership and permission to the newly created image:
 
#* Set correct ownership and permission to the newly created image:
 
#** <code>chown root:vm-storage my-vm.qcow2</code>.
 
#** <code>chown root:vm-storage my-vm.qcow2</code>.
 
#** <code>chmod 660 my-vm.qcow2</code>.
 
#** <code>chmod 660 my-vm.qcow2</code>.
 
#* Restore the VMs state:  <code>virsh restore my-vm.state</code>.
 
#* Restore the VMs state:  <code>virsh restore my-vm.state</code>.
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# Merge the disk images my-vm.qcow2 and my-vm-snap.qcow2 to a single image: <code>virsh qemu-monitor-command my-vm --hmp "block_stream drive-virtio-disk0"</code>.
 
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# Move the files to the backup location:
 
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#* Move the old disk image to the backup location and add the date as suffix to not overwrite older backups: <code>mv my-vm-backup.qcow2 /path/to/backup/my-vm-backup.qcow2.date</code>
 
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#* Move the state file to the backup location and add the date as suffix to not overwrite older backups: <code>mv my-vm.state /path/to/backup/my-vm.state.date</code>
 
  
 
== Merge ==
 
== Merge ==

Revision as of 13:49, 22 October 2013

Overview

This page describes how the VMs and VM-Templates are backed-up inside the stoney cloud.

Basic idea

The main idea to backup a VM or a VM-Template is, to divide the task into three subtasks:

  • Snapshot: Save the machines state (CPU, Memory and Disk)
  • Merge: Merge the Disk-Snapshot with the live-image
  • Retain: Export the snapshot files

A more detailed and technical description for these three sub-processes can be found in the following sub-chapters.

Snapshot

  1. Create a snapshot with state:
    • Save the state of VM vm-001 to the file vm-001.state: 
      virsh save vm-001 vm-001.stat
    • After this command, the VMs CPU and memory state is represented by the file vm-001.state and the VM vm-001 is shut down.
  2. Move the disk image /path/to/images/vm-001.qcow2 to the retain location: 
    mv /path/to/images/vm-001.qcow2 /path/to/retain/vm-001.qcow2
    • Please note: The retain directory (/path/to/retain/) has to be on the same partition as the images directory (/path/to/images/). This will make the mv operation very fast (only renaming the inode). So the downtime (remember the VM vm-001 is shut down) is as short as possible.
  3. Create the new (empty) disk image with the old as backing store file: qemu-img create -f qcow2 -b my-vm-backup.qcow2 my-vm.qcow2
    • Set correct ownership and permission to the newly created image:
      • chown root:vm-storage my-vm.qcow2.
      • chmod 660 my-vm.qcow2.
    • Restore the VMs state: virsh restore my-vm.state.

Merge

Retain

State of the art

Next steps

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