Some thoughts about backup for virtual machines running on Citrix XenServer 5.x.

1. Virtual Machine Backup
on Citrix XenServer 5.5
Thomas Krampe
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2. Virtual Machine Backup
on Citrix XenServer 5.5
Thomas Krampe
1

3. Overview
In some cases it might be very usefull to backup your virtual
machines running on a Citrix XenServer.
06/06/10 © 2010 Thomas Krampe
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4. Overview
In some cases it might be very usefull to backup your virtual
machines running on a Citrix XenServer.
There are several ways of backing up virtual machines (VMs).
At a very high-level, there are two major categories for VM backups:
06/06/10 © 2010 Thomas Krampe
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5. Overview
In some cases it might be very usefull to backup your virtual
machines running on a Citrix XenServer.
There are several ways of backing up virtual machines (VMs).
At a very high-level, there are two major categories for VM backups:
Cold Backups Hot Backups
Offline Online
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6. Introduction
Offline and Online backups are supported in Citrix XenServer through
XenCenter as well as through scripting from the command-line
interface (CLI).
The primary focus of this presentation are scheduled hot backups,
whereby virtual machines can be backed up without incurring
downtime.
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7. Introduction
Offline and Online backups are supported in Citrix XenServer through
XenCenter as well as through scripting from the command-line
interface (CLI).
The primary focus of this presentation are scheduled hot backups,
whereby virtual machines can be backed up without incurring
downtime.
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8. What‘s in the Box
There are also a lot of commercial applications and solutions out
there for doing this job (some links for more information at the end).
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9. What‘s in the Box
There are also a lot of commercial applications and solutions out
there for doing this job (some links for more information at the end).
But let‘s see what Citrix put in the box.
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10. What‘s in the Box
There are also a lot of commercial applications and solutions out
there for doing this job (some links for more information at the end).
But let‘s see what Citrix put in the box.
- Manual Exports through XenCenter and CLI
- Manual snapshots through XenCenter and CLI
- Scripted snapshots through XenAPI or CLI
06/06/10 © 2010 Thomas Krampe
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11. What‘s in the Box
There are also a lot of commercial applications and solutions out
there for doing this job (some links for more information at the end).
But let‘s see what Citrix put in the box.
- Manual Exports through XenCenter and CLI
- Manual snapshots through XenCenter and CLI
- Scripted snapshots through XenAPI or CLI
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12. Scripted Snapshot
XenServer VM snapshots can be made very simple from either the
XenServer (remote) CLI or through a XenServer API call.
Snapshots created in this way can use the Citrix VSS provider for
Windows VMs, which results in an application-consistent snapshot.
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13. Scripted Snapshot
XenServer VM snapshots can be made very simple from either the
XenServer (remote) CLI or through a XenServer API call.
Snapshots created in this way can use the Citrix VSS provider for
Windows VMs, which results in an application-consistent snapshot.
Pros:
• Fast
• Requires minimum of storage space
• Customizable to specific business needs
Cons:
• Requires additional knowledge of CLI or XenAPI
• More complicated file-level restoration
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14. Script Placement
There are two possible locations where we can execute our scripts.
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15. Script Placement
There are two possible locations where we can execute our scripts.
1. On the Administrator Workstation
- Windows Workstation with installed XenCenter
- VB Script for the logic
- Scheduled Tasks for automation
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16. Script Placement
There are two possible locations where we can execute our scripts.
1. On the Administrator Workstation
- Windows Workstation with installed XenCenter
- VB Script for the logic
- Scheduled Tasks for automation
2. On the XenServer
- XenServer Domain0
- Shell or Python Scripts for the logic
- Linux cron for automation
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17. Visual Basic Scripts
Advantages
- Running on Windows
- Use Visual Basic Script which is easy to use
- Can create backups in the local files system of the Workstation
Disadvantages
- Workstation has to be „always on“
- Network connection to Xenserver and maybe Storage required
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18. Shell or Python Scripts
Advantages
- Running on Domain0 Linux
- Very reliably with cron
- Server is in most cases „always on“
- Network connection to Storage is always there
Disadvantages
- Linux and Bash or Python knowledge required
- External Storage mandatory required
- Need Dom0 ressources while running
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19. Preparation
Before we can start we have to install an important piece of Software
on our virtual machines running Microsoft Windows.
To perform quiesced snapshots using Microsoft Volume Shadow Copy
Service we have to install the XenServer VSS Provider first.
Citrix provide us this piece of Software in the folder in which the
XenTools are installed, normaly under %SystemDrive%%Program
Files%CitrixXenTools. Just execute the batch script install-
XenProvider.cmd.
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20. Preparation
Before we can start we have to install an important piece of Software
on our virtual machines running Microsoft Windows.
To perform quiesced snapshots using Microsoft Volume Shadow Copy
Service we have to install the XenServer VSS Provider first.
Citrix provide us this piece of Software in the folder in which the
XenTools are installed, normaly under %SystemDrive%%Program
Files%CitrixXenTools. Just execute the batch script install-
XenProvider.cmd.
If you uninstall the XenTools quiesced Snapshots are not longer
available. After re-installing XenTools you have to install the
XenServer VSS Provider again. For an uninstall of the VSS
Provider simply execute the uninstall-XenProvider.cmd.
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21. Preparation
If we use a Windows VM to create snapshots we have to keep in mind
that, by default VMs only have access to their own snapshots.
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22. Preparation
If we use a Windows VM to create snapshots we have to keep in mind
that, by default VMs only have access to their own snapshots.
XenServer does a security check to prevent a VM from importing
another VMs disk without authority. Because in this scenario the VM
must have access to the snapshots of other VMs, we need to modify
the following parameter:
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23. Preparation
If we use a Windows VM to create snapshots we have to keep in mind
that, by default VMs only have access to their own snapshots.
XenServer does a security check to prevent a VM from importing
another VMs disk without authority. Because in this scenario the VM
must have access to the snapshots of other VMs, we need to modify
the following parameter:
xe vm-param-set other-config:snapmanager=true uuid=<uuid of VM used for backup>
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24. How to create a manual backup using XenCenter
Before we start scripting, just a small look on how we can do this
manually.
To create a snapshot in XenCenter just select the VM and go to the
Snapshot Tab. Now click the „Take Snapshot“ Button.
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25. How to create a manual backup using the CLI
Create Snapshot with quiesce
xe vm-snapshot-with-quiesce vm=<VM UUID> new-name-label=Backup
Create Snapshot without quiesce (normal snapshot)
xe vm-snapshot vm=<VM UUID> new-name-label=Backup
Remove the Template flag from the snapshot
xe template-param-set is-a-template=false uuid=<SNAPSHOT UUID>
Export the snapshot to backup share
xe vm-export uuid=<SNAPSHOT UUID> filename=<SHARE/file.xva>
Delete Snapshot from XenServer Host to safe space on SR
xe vm-uninstall uuid=<SNAPSHOT UUID> force=true
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26. Backup automation
Manual backups work great, but we want an scheduled, automated
live VM backup. Before start coding, let‘s take a look at the features
the script should have in addition.
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27. Backup automation
Manual backups work great, but we want an scheduled, automated
live VM backup. Before start coding, let‘s take a look at the features
the script should have in addition.
06/06/10 © 2010 Thomas Krampe
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28. Backup automation
Manual backups work great, but we want an scheduled, automated
live VM backup. Before start coding, let‘s take a look at the features
the script should have in addition.
1. External source for VM‘s to backup
2. Quiesced Snapshots (if possible) otherwise normal
3. Logging capabilities
4. External storage mount / dismount
5. Export snapshots to a network share
6. Clean up used Storage repository
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29. What to do?
I don‘t want to reinvent the wheel, so I found three great community
created scripts.
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30. What to do?
I don‘t want to reinvent the wheel, so I found three great community
created scripts.
Example 1: Visual Basic Script
Example 2: Bash Shell Script
Example 3: Python Shell Script
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31. Example 1: Visual Basic Script
The first script I found comes from Jeff Riechers and is based on
Visual Basic Script. The script is published in the Citrix Community
Forum.
http://forums.citrix.com/thread.jspa?threadID=250128&tstart=0
The script is very good documented and supports quiesced snapshots
if possible, 64bit Windows and is configureable with parameters.
Make sure that you read the full thread, there are a lot of usefull hints
inside.
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32. Example 2: Bash Shell Script
The second script comes from Andy Burton and is a bash shell script.
You can find this usefull script on the following website:
http://www.andy-burton.co.uk/blog/
The script is also very good documented and supports quiesced
snapshots if possible and is configureable with a configuration file.
You find a lot of enhancements like mounting / dismounting CIFS
shares and clearing old backups.
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33. Example 3: Python Script
The third script comes from David McArthur and is a Python script.
You can find this script on the following website:
http://community.citrix.com/display/xs/Zero-Downtime+Limited-Space+Backup
The python API is used to gather metadata about the VM, its disks,
and its network interfaces. The metadata is written to plain text
files. To restore, a new VM is created and given the memory and CPUs
settings stored in the metadata. Then the VIF and disks are restored
with the stored images being written to the new lvm volumes.
Currently, Windows servers are not supported in this version, only
Linux VMs and the XenServer instance, itself.
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34. My Results
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35. My Results
All of these three example scripts do their job as expected.
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36. My Results
All of these three example scripts do their job as expected.
1. VB Script
In my opinion the best way to create backups. If we install a
virtual Windows machine as a backup appliance with XenCenter
we can avoid the disadvantages (always on etc.)
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37. My Results
All of these three example scripts do their job as expected.
1. VB Script
In my opinion the best way to create backups. If we install a
virtual Windows machine as a backup appliance with XenCenter
we can avoid the disadvantages (always on etc.)
2. Bash Script
A very good script with many space for improvements. But scripts
running in the Dom0 Linux are in my opinion not a good idea.
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38. My Results
All of these three example scripts do their job as expected.
1. VB Script
In my opinion the best way to create backups. If we install a
virtual Windows machine as a backup appliance with XenCenter
we can avoid the disadvantages (always on etc.)
2. Bash Script
A very good script with many space for improvements. But scripts
running in the Dom0 Linux are in my opinion not a good idea.
3. Python Script
Good script but currently no support for Windows VM‘s
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39. Restore
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40. Restore
Backup is only the first part of the job. Some
times it‘s maybe very usefull to have also
the capabilities to restore a backup if the
original virtual machine is broken.
06/06/10 © 2010 Thomas Krampe
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41. Restore
Backup is only the first part of the job. Some
times it‘s maybe very usefull to have also
the capabilities to restore a backup if the
original virtual machine is broken.
All backup scripts as well as the manual way with XenCenter or CLI
creates a simple .xva file which can easy re-import.
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42. Restore
Backup is only the first part of the job. Some
times it‘s maybe very usefull to have also
the capabilities to restore a backup if the
original virtual machine is broken.
All backup scripts as well as the manual way with XenCenter or CLI
creates a simple .xva file which can easy re-import.
In most cases this re-import is being enough. But for a correct
restore you need also a backup of the virtual machine meta data
(MAC-Address or VCPU Settings for example).
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43. Restore Example
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44. Restore Example
Before perfoming a restore it‘s a good idea to uninstall the broken
machine first.
xe vm-uninstall uuid=<VM UUID> force=true
Then cleanup the Storage repository.
coalesce-leaf -u <VM UUID>
And restore the virtual machine.
xe vm-import filename=<BACKUP.XVA> preserve=true
If preserve is set to true, the MAC address of the original VM will be preserved.
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45. Enhancements
Here are some tips for enhancements.
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46. Enhancements
Here are some tips for enhancements.
1. Backup VM meta data
2. Check backup share first (free space, availability)
3. Cleanup backup share (old backups)
4. Create useful log files
5. Notfications (E-Mail, SMS)
.
.
.
x. Your ideas for improvements
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47. What‘s new in 5.6
Live Memory Snapshot and Rollback
- XenCenter support for live VM snapshot and revert
- One-click Revert
- Snapshot branches
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48. What‘s new in 5.6
New snapshot with memory feature
In addition to saving the VMs memory (storage) and
metadata, snapshots with memory also save the VMs state
(RAM).
xe vm-checkpoint vm=<VM UUID> new-name-label=<NAME>
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49. What‘s new in 5.6
New snapshot with memory feature
In addition to saving the VMs memory (storage) and
metadata, snapshots with memory also save the VMs state
(RAM).
xe vm-checkpoint vm=<VM UUID> new-name-label=<NAME>
During the checkpoint creation process, the VM is paused for a brief
period of time, and cannot be used during this period.
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50. Commercial Products
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51. Commercial Products
If you don‘t have time or fun for scripting and in addition have
unlimited budget, here are some commercial products.
QuorumSoft Alike
http://quorumsoft.com
PHD Virtual Backup for Citrix XenServer
http://www.phdvirtual.com
Symantec Backup Exec System Recovery Server Edition
http://www.symantec.com/de/de/business/backup-
exec-system-recovery-server-edition
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52. Contact Informations
For questions / suggestions after the Pubforum:
thomas.krampe@visionapp.de
More informations online:
www.thomas-krampe.com
in german only
Slides are available after the Pubforum at:
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53. Questions
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54. Questions
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55. Questions
Cheers
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