When I read recently that Virtual Server 2005 R2 SP1 will support Volume Shadow Copy Service (VSS) I was quite excited. This means that you can backup a running virtual machine without shutdowns. Some weeks ago I decided against Virtual Server 2005 and for VMware Server. However, VSS support is a killer feature in my view. Today, I tried to backup a running virtual Windows Server Virtual Server 2005 R2 SP1 Beta2 using Symantec Backup Exec 10d.

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Of course you can backup a virtual server like any other server by installing the backup agent on the guest system. The charm of backing up a virtual server on the host system is that disaster recovery is very fast. If your host system has hardware problems, you restore all virtual servers within minutes on another host with completely different hardware.

So I was quite curious to learn more about the VSS support of Virtual Server. I used the Backup Exec Advanced Open File Option which also supports VSS. I backed up a running virtual Windows Server 2003 system without any error messages.

I then deleted the virtual server and restored it using Backup Exec. The restored Windows Server booted without any problems. However, when I logged on, I got a message informing me that the system was shut down unexpectedly. The Windows Server worked perfectly, though.

But it is obvious that this is not the way it is supposed to work. The main problem with this method is that you can save the virtual machine files (.vmc .vhd . .vsv) of a running virtual server, but you can't save the system memory this way. So you might end up with a backup where the virtual machine files are not in a consistent state.

It is not enough if the backup software just supports VSS. It also has to support the new Virtual Server VSS Writer service (VS Writer). This VS Writer can be used by VSS requestors to back up and restore virtual machines. That way, backup software can inform Virtual Server that is going to backup a virtual machine and Virtual Server can create a snapshot before the copy process starts.

This is how the documentation of Virtual Server 2005 R2 SP1 describes the procedure:

In the console tree of the backup program, browse to Microsoft Virtual Server.
Expand Virtual Server.
Select the virtual machines that you want to archive.
Select the Virtual Server configuration for archive.
Select the backup type.
Select the media to which you want to back up the data.
Start the backup.

So you don't select the virtual machine files, but the virtual machine as a whole.

Symantec doesn't yet offer such an agent for Backup Exec supporting Virtual Server. I googled a little to see if there is any other backup software vendor offering an Virtual Server add-on already, but I didn't find any. I guess it won't take too long until the major vendors will have such products as soon as the final of Virtual Server 2005 R2 SP1 is available. Considering the description in the Virtual Server manual, it seems as if there is at least one working together with Microsoft since NTBackup won't support it.

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I am curious if VMware will offer something comparable in the new future. I still prefer VMware Server for many reasons. However, the possibility of being able to backup running virtual servers is a killer feature. Because of its high price, VMware ESX Server is not yet an option for us.

  1. ComputerMischief 15 years ago

    I love these discussions. On the one hand you have the IT Commando forging ahead proving time and time again that backing up a live Virtual Machine without suspending it first and all that happens is that Windows OS complains it wasn’t shutdown correctly as a flag wasn’t set to say that it was.

    On the other hand you have the nervous “but it does’nt back up what is currently in memory” therfore is not consistent. I beg to differ as Symantec Netbackup, Backup exec, Brightstor blah,blah clients do not do this either. They capture the system state information which isn’t superior, a mere collection of necessary systems bits and bobs inc registry, iis, boot info, com and dcom stuff etc, etc

    The point is a Commando IT engineer in a High availability environment, now has the ability to restore an entire machine in a couple of relatively hastle free minutes (When using disk staging) and without the complaints of VPN users that decide that midnight is the best time of day for them to work.

    Suspending every server for a short period every night might suit some, BUT who can actually say that in a server farm of 20 + servers all suspend + backup + unsuspend in 5-20 minutes, a little hopeful I feel. Plus what about when the thing gets stuck as you have to answer questions to get it going again.

    I am not fond of being lynched when I walk in in the morning as there is only 1st line IT Support where I work.

    Although of Course the IT Commando is a dead man if the server being backed up generates so much IO that the Volumes become corrupted (I have never seen this though). I have seen mild issue which are resolved by chkntfs /f, as during the backup data does change which leaves the ntfs bitmap a little confused as to where some files went and where these new ones came from.

  2. Trucking Nerd 15 years ago

    Hmm, IT Commando, that has a nice ring to it 🙂

    I’m very satisfied with what I’ve seen of the script and am rolling it out in my testbed now and fairly certain it will make it to my production environment before much longer.

    I also enjoy these discussions and collaboration…the synergies formed from the collective are invaluable!

  3. BulletproofSean 15 years ago

    My own testing supports your work Trucking Nerd. Here’s the problem though. If the state of these “hot backup virtual servers” is indeed the equivalent of pressing the reset button (as indicated by the requirement for giving a reason for the unexpected shutdown), and if booting from a VM saved in this manner results in failure 1 time in 20, that’s 1 time too many.

    And Computer Mischief – the backup systems you mention aren’t anything close to the same as backing up virtual machines from the outside. You can’t even compare them.

  4. Trucking Nerd 15 years ago

    Concur, have you seen any cases where you couldn’t boot the copied virtual server?

  5. BulletproofSea 15 years ago

    Not yet, but I’m trying. I _have_ had Virtual Servers have issues on boot after they were shutdown abrubtly either by host restarts due to power loss, or shutdown (reset or turn off) from the VS console. However, the difference with the backup script is that its invoking Shadow Copy first on each volume. We’ve already agreed internally that if I test bringing up virtual backed up servers 20 times (i.e. from 20 different saved machines, not 20 times on the same machine) with NO issues, then we’ll use it on production boxes.

  6. Trucking Nerd 15 years ago

    I’d be interested to learn if one of them is not bootable. I may do the same test on my side and will report back if I find anything different.

  7. SteveJHU 15 years ago

    We think we are having success here using Chris Wolf’s (Redmond Mag) script to execute VS Writer to create the snapshot. Question though…
    In Chris’ script, he copies the VHD files from the Volume Shadow Copy snapshot to another location, and his backup job backs up that location. Is it okay to just backup from the Volume Shadow Copy snapshot drive directly, instead of first copying the files out of there? We tested that, and restores seem to work. But I’m not sure if there’s something we’re missing that’s a reason why we should copy it first. Thanks.

  8. Marc 15 years ago

    I’ve tried to run this script on a server running 2005 R2 SP1 and when it runs the actual shadow copy component of the script, I watched it as it saved the state of each VM that was running on the server, not exactly what its supposed to do from how I read the script and article… or is it?

    My question is there anyway now that I’m running SP1 of Virtual Server to do a VSS copy in real time without the servers being “save stated”?

    It was possible prior to SP1 (we did it using a 3rd party tool that did VSS copies) and while I understand the implications of it being like “pressing reset”, this was acceptable to us for an emergency backup/restore scenario as it allowed us to make a backup of the image without having to turn it off.


  9. Sav 13 years ago

    I’m using BackupChain for Virtual Server 2005 as well as VMWare. It creates delta incremental files which only contain file changes and takes snapshots while the VMs are running. This way we save a lot of storage space and bandwidth because we send the backups via FTP to another server.

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