RCT Implementation

Question

Hi, we are trying to use the RCT implementation. Few questions related to it:

1. the query WMI GetVirtualDiskChanges or VHD QueryChangesVirtualDisk returns access_denied error for the full backup. Any idea on what is best to perform full backup ?
2. We tried the below procedure and found to get the corrupted disk.

> Create production snapshot using WMI
> then we manually Copied the vhdx file to some other directory (say c:\temp\vm1)
> Created reference point (say, RCT_id1).
> Delete snapshot
> Add files to guest os.
> Create snapshot again
> Run in GetVirtualDiskChanges query to get changed blocks since RCT_id1
> Read the blocks (offset/length) - (seek and read) to get the data to buffer.
> Write the buffer to c:\temp\vm1\ (saved in step 2) - overwrite
> Open the c:\temp\vm1\vm1.vhdx =====> This is corrupted.

Any help here is appreciated

Answer 1

Hi,

Your question is out of scope for this forum, since your question is related to the Windows API, I suggest you ask in the dedicated Windows API forum over here:
https://learn.microsoft.com/en-us/answers/topics/winapi-general.html

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(If the reply was helpful please don't forget to accept as answer, thank you)

Best regards,
Leon

Answer 2

Hope this article could be helpful
Hyper-V Backup Approaches
https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/hypervbackupapproaches

https://learn.microsoft.com/en-us/windows/win32/hyperv_v2/msvm-imagemanagementservice-getvirtualdiskchanges
https://learn.microsoft.com/en-us/windows/win32/api/virtdisk/nf-virtdisk-querychangesvirtualdisk