Bring Azure Vault Backup Data from MARS agent back on premise

Question

Bring Azure Vault Backup Data from MARS agent back on premise

Rob Ludlam 40

I have 20 TB of backup data in an Azure Backup Vault. This data is from the Microsoft Azure Backup Agent (MARS) from 2 on-premises servers. What is the best way for me to get this data back on premise and be able to recover if needed? Also, could I use an Azure Data box and have the data sent to me and just transfer to a NAS?

Accepted answer

0 additional answers

Your answer

Answer 1

Marcin Policht 46,770 MVP Moderator

To retrieve and recover 20 TB of backup data from an Azure Backup Vault (using the Microsoft Azure Recovery Services Agent) that was originally backed up from two on-premises servers, your options are limited due to the way MARS manages data. MARS data is encrypted with your passphrase and stored in a proprietary format inside the Recovery Services Vault. You cannot directly export this data using Azure Data Box from the vault — Microsoft does not support this. You must use the MARS agent with the correct passphrase to access and restore the data.

To work around it, consider the following:

Step 1: Create a temporary Azure VM

Spin up a Windows Server VM in Azure.
Install the MARS Agent on the VM.
Register the agent using the same Recovery Services Vault and passphrase used originally.

Step 2: Restore the data to the Azure VM

Use MARS to restore the files from Azure Backup Vault to the Azure VM.
This converts the encrypted/proprietary backup into regular files on disk.

Step 3: Copy Restored Data to On-Prem (Options Below)

Option A: Transfer via network

Mount an on-prem NAS share over VPN or ExpressRoute.
Use Robocopy, AzCopy, or similar tools to copy the restored files.

Option B: Use Azure Data Box

Order an Azure Data Box (e.g., 100 TB or 40 TB model).
Attach it to the Azure VM and copy restored data onto it.
Ship the Data Box to your data center.
Copy data from the Data Box to your NAS or target servers.

Step 4: Make the data recoverable on the original servers

You have two main paths:

Option 1: Manual recovery from NAS

Once the restored files are on a NAS:
- Access them from the original two servers.
- Manually move/copy the data back into application-specific locations.
- This works well for files, folders, SQL DBs (with export/import), etc.

Option 2: Re-register MARS agent and restore again

If needed, you can:
- Re-register the original on-prem servers with the same Recovery Services Vault and passphrase.
- Use the MARS agent locally to restore backup data directly from Azure (if you didn’t already purge it).
- But this method is slow and not ideal for 20 TB unless you're restoring smaller segments.

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin

Rob Ludlam 40 Reputation points

2025-05-08T14:19:17.9866667+00:00

Hi Marcin. Thank you for the detailed work arounds. Makes sense. I do have 2 more questions. I like the route of restoring to an Azure VM and then using the data box to get the data back on prem. I have date from 2016 in this vault. When restoring the data to the Azure VM with the MARS agent do I just pick the last good backup and restore it? Will that get everything all the way back to 2016? Or do I need to pick say the last of each year do the restore, then on the next year select "Do no recover the items that already exist on the recovery destination? How do I know I have it all but I do not want it multiple times?
Marcin Policht 46,770 Reputation points MVP Moderator

2025-05-08T15:16:52.9966667+00:00
excellent point - you should indeed take into account the backup history and restoring via the Azure VM + Data Box path.

MARS backups are:

Incremental: Only changes from the last backup are uploaded.

Snapshot-based: You can restore from any point-in-time recovery (based on your retention policy).

File-level: You select specific files/folders to restore from a specific backup date.

Q1: “Do I just pick the last good backup and restore it?”

Yes — if you want the latest state of all files, just selecting the most recent recovery point will usually give you everything that was still being backed up as of that point. However, if some files were deleted years ago and not present in the latest backup, they will not be restored unless you pick an older recovery point that still contains them.

So if your goal is to get all files ever backed up since 2016, including deleted/historic ones. You will need to restore from multiple points in time, going back to older recovery points.

Q2: “Do I need to pick one per year and merge? How to avoid duplicates?”

Yes, a safe and efficient way is to:

Start with the oldest backup point (e.g., from 2016 or 2017).

Restore all items to a base folder, e.g., D:\RestoredData\2016.

Move forward year by year (or quarter if needed), restoring each into a separate folder like:

D:\RestoredData\2017

D:\RestoredData\2018

…and so on.

On each restore, enable the option:

"Do not overwrite the files that already exist at the destination."

This prevents overwriting and lets you see if any unique files exist per restore window.

After all restores are done:

Use a duplicate file scanner (e.g., PowerShell, or tools like WinMerge, TreeSize, or RoboCopy /L) to:

Deduplicate files (same name, size, hash).

Identify files that were only available in earlier recovery points.

Optionally:

Merge everything into a final single folder (manually or via script).

Keep metadata (created/modified dates) for digital forensics if needed.

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin
Rob Ludlam 40 Reputation points

2025-05-08T18:04:13.3033333+00:00

Thank you so much Marcin. This was a huge help.

Share via

Bring Azure Vault Backup Data from MARS agent back on premise

0 additional answers

Your answer