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Olivier Lambert
2016-01-16 09:38:50 +01:00
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# Continuous Replication
> This feature is currently under active development.
> This feature is out since 4.12
Thanks to use of delta disks and VM streaming, we can provide a way to stream very often (ie almost continuously) disks to a remote pool.
This feature allow continuous replication system for your XenServer VMs without any storage vendor lock-in. You can now replicate a VM every xx minutes/hours on a any storage repository. It could be on a distant XenServer host or just another local storage.
Unlike DR, which is using a lot of bandwidth and can only be achieved sometimes, you can plan a replication every hour (and even every minute).
This feature covers multiple objectives:
* no storage vendor lock-in
* no configuration (agent-less)
* low Recovery Point Objective, from 10 minutes to 24 hours (or more)
* flexibility
* no intermediate storage needed
* atomic replication
* efficient DR (disaster recovery) process
If you lose your main pool, you can start the copy on the other side, with very recent data.
> Warning: only work on a clone of the copied VM. Indeed, you must avoid using directly this VM: as soon you'll start it, and if the diff continue to work, you can damage it.
![](https://xen-orchestra.com/blog/content/images/2016/01/replication.png)
Things left to do:
> Warning: that's normal you can't boot the copied VM directly: we protected it. The normal workflow is to make a clone and to work on it.
* secure/prevent the boot of the copied VM
* create a fast clone from it, instead of boot it
* use blocked operations
## Configure it
As you'll see, this is trivial to configure. Inside the "Backup" section, select "Continuous Replication":
![](https://xen-orchestra.com/blog/content/images/2016/01/continuous_replication.png)
Then:
1. Select VMs you want to protect
1. Schedule the replication interval
1. Select the destination storage (could be any storage connected to any XenServer host!)
![](https://xen-orchestra.com/blog/content/images/2016/01/continuous_replication2.png)
> In this case, we'll replicate 2 VMs to "NFS" SR which is a pool called "Other Pool". Replication will happen every 20 minutes.
That's it! Your VMs are protected and replicated as requested.
To protect the replication, we removed the possibility to boot your copied VM directly, because if you do that, it will break the next delta. The solution is to clone it if you need it (a clone is really quick). You can do whatever you want with this clone!
![](https://xen-orchestra.com/blog/content/images/2016/01/remplication_small.png)