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Backup live Hyper-V Servers

I have a number of virtual servers whose entire images I'd like to backup for disaster recovery purposes without having to take them offline.

Can someone tell me if this is possible to do? I'm thinking it might go something like:

1) Take snapshot of live server
2) Backup the .vhd file and other files....? (What files do I need?)
3) Remove the snapshot and merge the changes

All the Hyper-V related files are on the same volume.

I don't at this point want to use VSS and Windows Server Backup (for space reasons) since I think you have to back up the entire volume.


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2 Solutions
I don't think there is a way to backup the VMs without using VSS. You either go by third party softwares or windows native backup, they invoke VSS in the back ground.

As for the third party softwares, you can go for CA ARCserve backup 12.5 version. They are coming with good features for Hyper V backup. You need to have some of the free disk space for the snapshot file to be stored temporarily.

Syed Mutahir AliTechnology ConsultantCommented:
Having recently implemented Hyper-V, what I did was the following :

a) Once I created the guest OS in a fully functional server (without implementing AD inside it), installed applications and all, did a sysprep and called it base.vhd, sysprep it and shutdown.

Once the vm shutdown, I then simply copied Sysdisk.vhd to a external storage.

This way I can recover the OS in no time as it has a copy on the local server and on the external storage as well.

Secondly, you can implement Symantec Backup Exec with virtual agents to pull data off the VMs ; in the past I have used simple windows backup as well to pull data off the vm's when we didn't have the symantec backup exec agents.

You can simply copy the VHDs as well, and also the VM config files as well, so that when you re-implement the Hyper-V environment you can then point to the VM Config ; or if you dont want to copy the vm config you can simply attach the VHDs again and it works.
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shofarsleeAuthor Commented:
Two questions:

1) If I take a snapshot, what files do I need to backup (and which can I ignore) so that I can "wake up" the virtual server on another Hyper-V Host with mimimal configuration?

2) Also, if there is a database running on the server at the time of the snapshot, will the snapshot process preserve the integrity of the database in the vhd file?
1. All you need to backup is VHD and VM Config files. You need avhd when you want those snapshot state.

2. There is NO guarantee for the Database integrity but most of the times, it works fine. The reason being is the writer that is backing up the VHD is not designed to keep the Database integrity. I have done a restore of a VHD running test Exchange 2007 and it was working fine after the restore, so i cant say that it wont work at all.
Syed Mutahir AliTechnology ConsultantCommented:
There is a whole Hyper-V snapshot FAQ at the following link :
and this link has good info as well : http://blogs.msdn.com/virtual_pc_guy/archive/2008/01/16/managing-snapshots-with-hyper-v.aspx

No, because virtual machine snapshots are not the same as backups created by a Volume Shadow Copy Service (VSS) writer. We do not recommend using virtual machine snapshots as a permanent data or system recovery solution. Even though virtual machine snapshots provide a convenient way to store different points of system state, data, and configuration, there are some inherent risks of unintended data loss if they are not managed appropriately. A backup solution helps provide protection that is not provided by snapshots.

One reason that snapshots are not an acceptable substitute for a backup is that they do not protect against problems that may occur on the server running Hyper-V, such as a hardware malfunction on the physical computer or a software-related issue in the management operating system. Another reason is that applications that run in a virtual machine are not aware of the snapshot, and will not be able to adjust appropriately. For example, if you used a virtual machine snapshot to restore an Exchange server, the server would expect the same set of client connections that were present when the snapshot was taken.
Hope this helps
shofarsleeAuthor Commented:
Thanks for the various replies and links. In addition to your answers, here's some additional context as well as results from some more research:

1) The reason for using snapshots to do backups is NOT because I want to backup the snapshot. It is solely so that I can "freeze" the .vhd file so that it can be backed up safely.

Thus, by taking a snapshot, I get a .vhd file that is "static" and thus ready to be copied to my backup location.

2) The problem: once I have taken the Hyper-V snapshot and copied the .vhd file (and config files), there is no way to merge the snapshot back into the .vhd file unless I take it offline.

Therefore, the ultimate answer is that you can only backup the server online once using Hyper-V snapshots (the very first snapshot you take). After that, you must delete the snapshot and then shutdown or suspend the virtual server to force the merge of the snapshot (.avhd) data into the main .vhd file.

So, my final solution for backing up the .vhd files with minimal downtime (but not zero downtime) is this:
1) Take Hyper-V snapshot of virtual guest server
2) Copy the .vhd file to another location
3) Delete the snapshot
4) Shutdown virtual guest server to allow merge
5) Restart server virtual guest server

This requires downtime between steps 4 and 5. Otherwise, I would have to shut down the virtual server. Copy the .vhd, and then restart it - which would be much longer downtime.

shofarsleeAuthor Commented:
I know this question is closed but in case anyone else is searching for similar information, you really need to consider Data Protection Manager which is part of Microsoft System Center.  The price tag is not unbearable at all (about $500 per server) and the feature set is virtually (no pun intended) untouchable.


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