Recover VM from virtual disk on local storage

[Brandon Sloan1709160000]

I have had to reinstall Xen on my server and I have managed to get the local storage reattached and I can see the virtual disk for the old VM's in the local storage... Is it possible to recover the VM's from those virtual disk?

 

[Tobias Kreidl]

Hmmm, typically when you create a boot device or any other VDI on one VM, detaach it, and re-attach it to another VM, it should be able to pick it up providing it's the same OS installation.

The metadata isn't essential only helpful identifying the origin. Do you have any exported VMs you could import and try this with? Is the new XenServer install fully patched?

[Tobias Kreidl]

Yes, you as long as it has not been reformatted. See: https://support.citrix.com/article/CTX136342

on how to reinstall XenServer and preserve the earlier local SR. But you must do this during the installation process otherwise the old

SR will be recreated and wiped clean. For future reference, having VMs and the metadata backed up is always a good idea.

 

-=Tobias

[Brandon Sloan1709160000]

1 hour ago, Tobias Kreidl said:

Yes, you as long as it has not been reformatted. See: https://support.citrix.com/article/CTX136342

on how to reinstall XenServer and preserve the earlier local SR. But you must do this during the installation process otherwise the old

SR will be recreated and wiped clean. For future reference, having VMs and the metadata backed up is always a good idea.

 

-=Tobias

I have followed these steps and that is how I got to where I am.  When I get to restore the mapping manually section it ask you to create the VM's from a template and to delete the default drives.  That option is grayed out for me and I am unable to do that.  I have created the VM's and then deleted the default volume after the fact and then attached the old volume but when trying to start the VM I get the error "an emulator required to run this VM failed to start".

[Tobias Kreidl]

What you posted deals with a new VM's storage on an existing SR, not the default local SR configuration when XenServer was first re-installed. Did you initialize the local storage SR when you rebuilt XenServer?

[Brandon Sloan1709160000]

14 minutes ago, Tobias Kreidl said:

What you posted deals with a new VM's storage on an existing SR, not the default local SR configuration when XenServer was first re-installed. Did you initialize the local storage SR when you rebuilt XenServer?

I have followed the steps in the link you sent and I am at the point of restoring the mappings manually with no metadata backup.  The first thing it ask you to do in that process is to create a new VM from a template and to delete the default volume which to which I attached a picture showing that options is grayed out and unavailable. 

 

I went ahead and created a new VM from a template as suggested and then deleted the volume after the fact and then reattached the old volume to that VM which is what one of the other pictures shows. That VD is from one of the machines I want to restore, it was not recreated by me and it has the same naming convention and size as what was there previously.  The other picture is the error I get when trying to start the new VM from the template with the old VD attached.

[Brandon Sloan1709160000]

8 minutes ago, Tobias Kreidl said:

Hmmm, typically when you create a boot device or any other VDI on one VM, detaach it, and re-attach it to another VM, it should be able to pick it up providing it's the same OS installation.

The metadata isn't essential only helpful identifying the origin. Do you have any exported VMs you could import and try this with? Is the new XenServer install fully patched?

It is actually not fully patched, I had just thought of that a few minutes ago and I am in the process of doing it now.

 

I could export one from another host and try if you think i should?  Are you thinking of doing that just to see that the host is OK since that's a differewnt scenario than what I am trying to do?

[Tobias Kreidl]

As to making sure any VM will run on your new host, yes, that's indeed my thought.

[Brandon Sloan1709160000]

On 3/10/2021 at 3:29 PM, Tobias Kreidl said:

As to making sure any VM will run on your new host, yes, that's indeed my thought.

After installing the patches I was able to get the old VM's to boot, thanks for your help!

[Tobias Kreidl]

1 hour ago, Brandon Sloan1709160000 said:

After installing the patches I was able to get the old VM's to boot, thanks for your help!

Brandon,

Ah, great news! That's one thing I suspected. Please mark as resolved so that this may assist others in the future. Very glad to hear that helped you out!

 

-=Tobias