How to backup OS disk?

Question

How to backup OS disk?

Handinata Tanudjaja 170

Hi all,

I have a VM that's being encrypted with encryption at host.
And I have set up with it with standard default policy backup to a recovery service vault.

What I am trying to do is to just to manual backup via the azure portal by selecting "Backup now" ,which seems to be that it's working because I could see the Backup jobs.
However when after the backup jobs completed, I don't see any new OS disk backup at all.

Do I have to use another method to backup the OS disk?

Thank you

Naveena Patlolla 975 Reputation points Microsoft External Staff

2025-03-03T18:35:53.74+00:00

Hi Handinata Tanudjaja
Welcome to Microsoft Q&A Forum, thank you for posting your query here!

You don’t need to manually back up the OS disk separately, as the backup process for the entire VM (including the OS disk) should work fine even with encryption at host. If you don’t see the OS disk explicitly, it's likely due to how the backup jobs are visualized, but it should be part of the full VM backup in the Recovery Services Vault.

To confirm whether the OS disk has been backed up, restore the VM in a Test Virtual Network—an isolated network that is not connected to any other network

Feel free to reach out if you have any further questions or need additional information—I’m happy to assist!

If you have any further queries, do let us know

If the answer is helpful, please click "Upvote it"
Handinata Tanudjaja 170 Reputation points

2025-03-04T02:04:31.5033333+00:00

Hi Naveena,
Thank you for your response.
My main focus is on the "Swap OS Disk" because I need to be able to switch to a backup OS disk.
However when I chose "Swap OS disk" or through "Get-AzDisk" Powershell command, there's no new backup OS disk at all.

3 answers

Your answer

Naveena Patlolla 975 Reputation points Microsoft External Staff

2025-03-03T18:35:53.74+00:00

Hi Handinata Tanudjaja
Welcome to Microsoft Q&A Forum, thank you for posting your query here!

You don’t need to manually back up the OS disk separately, as the backup process for the entire VM (including the OS disk) should work fine even with encryption at host. If you don’t see the OS disk explicitly, it's likely due to how the backup jobs are visualized, but it should be part of the full VM backup in the Recovery Services Vault.

To confirm whether the OS disk has been backed up, restore the VM in a Test Virtual Network—an isolated network that is not connected to any other network

Feel free to reach out if you have any further questions or need additional information—I’m happy to assist!

If you have any further queries, do let us know

If the answer is helpful, please click "Upvote it"
Handinata Tanudjaja 170 Reputation points

2025-03-04T02:04:31.5033333+00:00

Hi Naveena,
Thank you for your response.
My main focus is on the "Swap OS Disk" because I need to be able to switch to a backup OS disk.
However when I chose "Swap OS disk" or through "Get-AzDisk" Powershell command, there's no new backup OS disk at all.

Answer 1

TP 109.2K

Hi,

Backing up the VM includes the OS disk as well as data disks (unless you excluded data disks from backup).

If you only want to restore disk, navigate to the VM -- Backup + disaster recovery -- Backup blade. On the right side, click on the context menu (three dots) to the right of the backup you would like to restore and choose Restore VM.

User's image

On the Restore Virtual Machine screen, select Restore target: Create new, change Restore type: to Restore disks, select Resource group you would like to restore it to, and the storage account you would like to use for staging purposes, then click Restore button.

restore vm screen

You may view status of the restore via Backup blade -- View jobs link. Once restore has finished the restore disk(s) will be in the resource group.

Please click Accept Answer and upvote if the above was helpful.

Thanks.

-TP

Handinata Tanudjaja 170 Reputation points

2025-03-03T18:29:39.52+00:00

Hi TP,
Thank you for your reply.
My question is on how to back up OS disk.
The reason I found out the OS disk didn't get back up is because when I chose "Swap OS Disk", I didn't see any new VM's OS disk backup after I did the "Backup now."

Thank you
TP 109.2K Reputation points

2025-03-03T18:41:02.55+00:00

My question is on how to back up OS disk. The reason I found out the OS disk didn't get back up is because when I chose "Swap OS Disk", I didn't see any new VM's OS disk backup after I did the "Backup now."

You mention you did Backup now. After you verified that the backup had completed, did you restore the VM?

Backup now tells it to perform a backup of the VM (including its disks) as soon as possible. Once finished, there is a backup of the VM, but this doesn't create any managed disks in your resource group.

The steps I describe above are what will create a new OS disk in the resource group.
Handinata Tanudjaja 170 Reputation points

2025-03-04T01:55:20.7166667+00:00

Hi TP,
Yes, I have verified the backup jobs were completed.
I haven't tried the restore VM because my main focus is the "Swap OS Disk."
I will need to be able to swap with backup OS disk but I don't see any new backup OS disk whenever I did "Backup now."
TP 109.2K Reputation points

2025-03-04T02:01:57.08+00:00

Yes, I have verified the backup jobs were completed. I haven't tried the restore VM because my main focus is the "Swap OS Disk." I will need to be able to swap with backup OS disk but I don't see any new backup OS disk whenever I did "Backup now."

Go ahead and do Restore VM with Create new and Restore disks option as I show in screenshot above, and a new OS disk will be put in resource group. After that you can test Swap OS disk.

Please give the steps a try and let me know the result. If something is unclear I will assist you.
Handinata Tanudjaja 170 Reputation points

2025-03-04T22:13:00.18+00:00

Thanks TP.
Just like you mentioned a new restored disk will be created after you did a restore VM with the "Restore disks" option in the "Restore Type."
It's interesting that it has this approach but it's not how I want to make the backup OS disk to be available.
I do find another way from Microsoft documentation to create a backup OS disk to be available which I will provide as a different comment.
TP 109.2K Reputation points

2025-03-04T22:25:31.33+00:00

Thanks TP. Just like you mentioned a new restored disk will be created after you did a restore VM with the "Restore disks" option in the "Restore Type." It's interesting that it has this approach but it's not how I want to make the backup OS disk to be available. I do find another way from Microsoft documentation to create a backup OS disk to be available which I will provide as a different comment.

There are multiple ways to backup/restore. What I posted is only one method.For example, you could navigate to Restore point blade, click on one of the restore points, and restore a copy of OS disk that way.

Or, if VM is stopped, you could create snapshot of OS disk, which is effectively a crash-consistent copy of the OS disk, and then create a disk from this snapshot.

Answer 2

Vinod Pittala 735 Microsoft External Staff

Hello Handinata Tanudjaja,

If you had successfully completed the restore operation from the recovery services vault, you would see the restored (Backed up) OS disk in the RG or on the Disk's page.

To find the newly restored disk, you can redirect to Azure Disks page and check if the restored disk is available there or not? If you are still unable to see the restored disk, verify whether the restore operation is completed or not?

To do this, go to the backup jobs and check for the restore operation as shown below. User's image

Once the restore operation is completed successfully, you must have seen the restored OS disk when you do the "Swap OS disk" from the VM page, as shown below. User's image

If you still cannot see this, do the restore disks operation as shown in below. and verify the same. User's image

Hope this helps!

let us know if you have any further queries. I’m happy to assist you further.

Please provide your valuable comments

Please do not forget to "Accept the answer” wherever the information provided helps you, this can be beneficial to other community members.

Thanks

Handinata Tanudjaja 170 Reputation points

2025-03-04T22:14:16.6966667+00:00

Thanks Vinod.
You have the same approach as TP. I will share what I found through Microsoft documentation.
Thanks again for answering.
Handinata Tanudjaja 170 Reputation points

2025-03-04T22:23:04.6533333+00:00

Thank you for all the inputs.
I was looking another way to make the new backup OS disk to be available other than through "Restore VM" route.

I found out there's a way to do it via this method in the documentation:
https://learn.microsoft.com/en-us/azure/virtual-machines/snapshot-copy-managed-disk?tabs=portal
https://learn.microsoft.com/en-us/azure/virtual-machines/attach-os-disk?tabs=portal

Create a snapshot of the current OS disk and then create a new disk based on the snapshot.
Vinod Pittala 735 Reputation points Microsoft External Staff

2025-03-05T05:57:21.6566667+00:00

Hello Handinata Tanudjaja,

Swapping the OS disk can be achieved either by restoring the OS disk from a backup or by creating the OS disk from a disk snapshot. each method has its own advantages and considerations, depending on the specific requirements of your scenario.

Here is the clear explanation for you.

If you restore the OS disk from the backup, it will allow you to a specific point in time, which can be crucial if you need to revert to a known good configuration. Backups can be configured to be application-consistent,

So, if you require application consistency, need to restore to a specific point in time i.e. restoring from a backup is more appropriate.

Whereas, Snapshots can be restored faster than backups, enabling quicker recovery times. so that the process of creating a new disk from a snapshot is straightforward and snapshots are incremental, so its storage costs may be lower compared to backups.

however, the snapshots might not be application-consistent unless the VM was stopped or the application was quiesced at the time the snapshot was taken.

If you need a quick recovery solution, and application consistency is not a major concern (or you can ensure consistency during the snapshot process), using a disk snapshot is often the preferred method due to its speed and simplicity.

Note: By approaching these two methods you can be able to swap the OS disk from the VM page.

Hope this helps!

let us know if you have any further queries. I’m happy to assist you further.

Please provide your valuable comments

Please do not forget to "Accept the answer” and “upvote it” wherever the information provided helps you, this can be beneficial to other community members.it would be greatly appreciated and helpful to others.

Thanks

Answer 3

Hi Handinata Tanudjaja

I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others", I'll repost your solution in case you'd like to "Accept " the answer.