How to restore a Virtual Machine's disk after the VM crashed?

Question

How to restore a Virtual Machine's disk after the VM crashed?

Benjamin Rommel 40

Hello,

Last week, one of our Virtual Machines in Azure was rebooted causing a several hours long continuous crashing and rebooting until a Microsoft bot or employee fixed it at night.

The VM is now available again and I can connect via RDP, but the second disk where we placed all of our websites appears to be damaged? The disk shows up in the Windows Disk Management, but it shows up as unallocated.

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Is there a way to add the Disk again with the data it had before the VM crashed without formatting it?

TP 155.7K Reputation points Volunteer Moderator

2025-06-16T13:10:51.7533333+00:00

Hi Benjamin,

Do you have a backup and/or snapshot of the disk prior to the corruption?

Another potential option would be to make snapshot, create disk from snapshot, attach this new disk to separate vm, and use third-party data recovery software to see if you can repair/recover partitions.
Benjamin Rommel 40 Reputation points

2025-06-16T19:06:46.17+00:00

Hello TP, unfortunately, I do not have a snapshot of the hard drive. We were still in the process of setting everything up production and although we were very advanced in the process, it was not yet concluded and therefore, we do not have a snapshot.

If the drive is not recognized, does it mean all data is lost?
TP 155.7K Reputation points Volunteer Moderator

2025-06-16T19:18:22.8966667+00:00

If the drive is not recognized, does it mean all data is lost?

You won't know until you try data recovery program. A recovery program might scan the drive and find the old partition(s) and then recover them. This is similar to physical PC drive where the drive/data was fine and then suddenly because of some power failure or weird glitch it comes up showing as nothing on the drive, even though the drive itself isn't giving errors when you run manufacturer diagnostic. If something happened that corrupted partition table often (not always) one of these recovery utilities can repair it. It's worth trying unless it would be relatively easy for you to redo the data.
Benjamin Rommel 40 Reputation points

2025-06-16T19:32:25.2+00:00

This is a duplicate. Sorry.
Benjamin Rommel 40 Reputation points

2025-06-16T19:42:56.5166667+00:00

When I open Disk Management on the Virtual Machine, I can see the second drive, but it is offline.

When I navigate in Azure inside the Virtual Machine Resource to Settings > Disk, I see only one 256 GB hard drive. Now, when I take a snapshot of the only disk I see here, create a new disk using the snapshot, and attach this new disk to the same Virtual Machine, I get this:

I have now the same Windows disk twice, but not the corrupted drive. If the Disk shown in Azure is only the OS drive, then where is the corrupted drive?
TP 155.7K Reputation points Volunteer Moderator

2025-06-16T19:47:53.3866667+00:00

In the Azure portal, if you navigate to the VM -- Settings -- Disks blade, is your original data disk attached? Please also navigate to the resource group where your VM is and check what disk(s) are present, perhaps your missing data disk is there just not attached to your VM.

What precise VM size was your VM? I know it was a v6 since you were affected by that issue, but which precise size was it?
Benjamin Rommel 40 Reputation points

2025-06-16T19:56:04.6133333+00:00
Hello TP, I only had one Disk visible under Settings > Disks before I added a snapshot disk (as shown above). In the past I also only ever had one Disk Resource for this Virtual Machine. I am very certain about this.

As for my Resource Group, I have the following Resources for my VM:

Virtual machine

Public IP address

Network security group

Network Interface

Disk

We are currently using two separate VMs in the same Resource Group so I have all the Resources above twice. The second VM has the same issue. The D drive only shows up as unallocated space and I can see the one Disk I ordered with the VM.
TP 155.7K Reputation points Volunteer Moderator

2025-06-16T20:15:46.1066667+00:00

Which precise VM size are you using now, and which precise VM size were you using before? Availability + scale -- Size blade

Certain VM sizes include local NVMe volatile disks, some include local temporary disks (also volatile), etc. If I know precise size you are/were using I can look up and confirm what your size includes. There is possibility you stored all of your files on a volatile disk. If this is true it would be lost when your VM was Deallocated or when it was moved to different physical host.

Normally, you create and attach a separate data disk (either during VM creation or after) and store various files there. If you are certain you didn't do this, then we have to figure out where exactly you stored all of your files. If you stored it on an included local volatile disk, then the files are gone.
Benjamin Rommel 40 Reputation points

2025-06-16T20:22:12.6233333+00:00

Hello, the area under "Availability + scaling" on the dashboard is empty. The "Size" of the Virtual Machine as listed on the dashboard is "Standard E4ads v6".

My Disk has "Disk tier" P15, a "Size" of 256 GiB, and a "Storage type" of Premium SSD LRS as shown on the Resource's dashboard.

What I did for the Virtual Machine was: I added the P15 Disk when I ordered the Virtual Machine. Then, when logged into the VM via RDP, I ran diskmgmt.msc, confirmed the dialog that a drive is not allocated, formatted it, and assigned drive D to it. I was always assuming this was the drive that I ordered together with the VM as it showed 256 GB of space and it was in addition to the space of the other drive. Or was I mistaken?

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TP 155.7K Reputation points Volunteer Moderator

2025-06-16T13:10:51.7533333+00:00

Hi Benjamin,

Do you have a backup and/or snapshot of the disk prior to the corruption?

Another potential option would be to make snapshot, create disk from snapshot, attach this new disk to separate vm, and use third-party data recovery software to see if you can repair/recover partitions.
Benjamin Rommel 40 Reputation points

2025-06-16T19:06:46.17+00:00

Hello TP, unfortunately, I do not have a snapshot of the hard drive. We were still in the process of setting everything up production and although we were very advanced in the process, it was not yet concluded and therefore, we do not have a snapshot.

If the drive is not recognized, does it mean all data is lost?
TP 155.7K Reputation points Volunteer Moderator

2025-06-16T19:18:22.8966667+00:00

If the drive is not recognized, does it mean all data is lost?

You won't know until you try data recovery program. A recovery program might scan the drive and find the old partition(s) and then recover them. This is similar to physical PC drive where the drive/data was fine and then suddenly because of some power failure or weird glitch it comes up showing as nothing on the drive, even though the drive itself isn't giving errors when you run manufacturer diagnostic. If something happened that corrupted partition table often (not always) one of these recovery utilities can repair it. It's worth trying unless it would be relatively easy for you to redo the data.
Benjamin Rommel 40 Reputation points

2025-06-16T19:32:25.2+00:00

This is a duplicate. Sorry.
Benjamin Rommel 40 Reputation points

2025-06-16T19:42:56.5166667+00:00

When I open Disk Management on the Virtual Machine, I can see the second drive, but it is offline.

When I navigate in Azure inside the Virtual Machine Resource to Settings > Disk, I see only one 256 GB hard drive. Now, when I take a snapshot of the only disk I see here, create a new disk using the snapshot, and attach this new disk to the same Virtual Machine, I get this:

I have now the same Windows disk twice, but not the corrupted drive. If the Disk shown in Azure is only the OS drive, then where is the corrupted drive?
TP 155.7K Reputation points Volunteer Moderator

2025-06-16T19:47:53.3866667+00:00

In the Azure portal, if you navigate to the VM -- Settings -- Disks blade, is your original data disk attached? Please also navigate to the resource group where your VM is and check what disk(s) are present, perhaps your missing data disk is there just not attached to your VM.

What precise VM size was your VM? I know it was a v6 since you were affected by that issue, but which precise size was it?
Benjamin Rommel 40 Reputation points

2025-06-16T19:56:04.6133333+00:00

Hello TP, I only had one Disk visible under Settings > Disks before I added a snapshot disk (as shown above). In the past I also only ever had one Disk Resource for this Virtual Machine. I am very certain about this.

As for my Resource Group, I have the following Resources for my VM:

Virtual machine

Public IP address

Network security group

Network Interface

Disk

We are currently using two separate VMs in the same Resource Group so I have all the Resources above twice. The second VM has the same issue. The D drive only shows up as unallocated space and I can see the one Disk I ordered with the VM.
TP 155.7K Reputation points Volunteer Moderator

2025-06-16T20:15:46.1066667+00:00

Which precise VM size are you using now, and which precise VM size were you using before? Availability + scale -- Size blade

Certain VM sizes include local NVMe volatile disks, some include local temporary disks (also volatile), etc. If I know precise size you are/were using I can look up and confirm what your size includes. There is possibility you stored all of your files on a volatile disk. If this is true it would be lost when your VM was Deallocated or when it was moved to different physical host.

Normally, you create and attach a separate data disk (either during VM creation or after) and store various files there. If you are certain you didn't do this, then we have to figure out where exactly you stored all of your files. If you stored it on an included local volatile disk, then the files are gone.
Benjamin Rommel 40 Reputation points

2025-06-16T20:22:12.6233333+00:00

Hello, the area under "Availability + scaling" on the dashboard is empty. The "Size" of the Virtual Machine as listed on the dashboard is "Standard E4ads v6".

My Disk has "Disk tier" P15, a "Size" of 256 GiB, and a "Storage type" of Premium SSD LRS as shown on the Resource's dashboard.

What I did for the Virtual Machine was: I added the P15 Disk when I ordered the Virtual Machine. Then, when logged into the VM via RDP, I ran diskmgmt.msc, confirmed the dialog that a drive is not allocated, formatted it, and assigned drive D to it. I was always assuming this was the drive that I ordered together with the VM as it showed 256 GB of space and it was in addition to the space of the other drive. Or was I mistaken?

Answer 1

TP 155.7K Volunteer Moderator

Hi,

Based on your last comment I'm afraid your data is lost.

In general (not in 100% cases, but most), when you create VM at a minimum you have to choose OS disk, and this is separate charge. Depending on your needs, you may choose to attach one or more data disks, which also are a separate charge.

Standard_E4ads_v6 includes a local 220 GiB NVMe temporary disk as part of the hourly compute charge. It is great option for certain workloads that need fast local storage, but it isn't for storing permanent data. Reason is, if/when you Deallocate your VM, all data is lost, or if VM gets moved to another physical host via redeploy or platform maintenance/health event, all data is lost.

Bottom line, for files/data that you need/expect to stick around you need to save them on the OS disk or preferably data disk(s). On top of that you should consider which redundancy option you choose for your disks as well as enable backups.

Below article shows you specifications of Eadsv6 series VMs, for reference:

https://learn.microsoft.com/en-us/azure/virtual-machines/sizes/memory-optimized/eadsv6-series?tabs=sizestoragelocal#sizes-in-series

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

Thanks.

-TP

Benjamin Rommel 40 Reputation points

2025-06-17T15:26:36.67+00:00

Thank you. It is very unfortunate that our data is lost, but I know set up everything correctly with a second drive for each VM. Thanks for your support.
TP 155.7K Reputation points Volunteer Moderator

2025-06-17T15:37:45.35+00:00

Thank you. It is very unfortunate that our data is lost, but I know set up everything correctly with a second drive for each VM. Thanks for your support.

You are welcome. The NVMe case is different than traditional local temporary disk in that you have to partition/format it and there is no warning of loss. Traditional temp disk is automatically formatted and has drive letter assigned with a file named DATALOSS_WARNING_README.txt in the root. This file warns you that the disk is temporary and subject to loss with no way to recover.Benefit of NVMe temp disk over the older temp disk is it is much faster.

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How to restore a Virtual Machine's disk after the VM crashed?

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