How to back up a VM on a Hyper-V volume larger than 64TB

[Asahi]

Hi,

I have a user in a Hyper-V 2019 environment with a Hyper-V host volume of over 100TB.
They are trying to deploy VMs and perform backups on this volume.
Hyper-V is running in a standalone configuration and the proxy is running in on-host proxy mode.

And Veeam is using Veeam v11a.

The operating system of the VM is Windows Server 2012 R2, and it has about 3TB of disk space allocated to it.
The VM is in shutdown state, and Veeam backup job is set in crash consistent mode.

I performed a backup, but the checkpoint creation operation failed.

===
2021/12/20 0:40:00 :: Failed to create VM recovery checkpoint (mode: Crash consistent) Details: Unknown status of async operation The shadow copy provider had an error. Check the System and Application event logs for more information.
--tr:Failed to create VSS snapshot.
--tr:Failed to perform pre-backup tasks.
===

And the following error was output to the Windows Event Log of Hyper-V Host 2019.
===
Event ID: 12289
===

When I exported the log, the "SnapshotCreator.log" file was generated and VSS was running on Hyper-V host 2019 and failed.

However, I believe that VSS on the Hyper-V host does not work when backing up in on-host proxy mode in crash consistent mode in Windows Hyper-V 2016 or later.
https://helpcenter.veeam.com/docs/backu ... -and-later

Also, as far as I can tell from the user guide, while Hyper-V 2012 R2 and earlier has a limit on host volume capacity, I believe Hyper-V 2016 and later has no such limit.
https://helpcenter.veeam.com/docs/backu ... er=110#vms

So I asked a user to test if I could create a checkpoint on Hyper-V manually.
The manual checkpointing operation was successful.

However, one point of concern is that the user's VM has a Configuration Version of 5.0.
In my Hyper-V 2016 Lab environment, I prepared VMs with Configuration Version 5.0 and 8.0 respectively.

When I backed up with on-host proxy in crash consistent mode, only the job with Configuration Version 5.0 output the "SnapshotCreator.log" log file.
Looking at the "SnapshotCreator.log" log file, it seemed that VSS was running on the Hyper-V host.

The "SnapshotCreator.log" file was not output for the VM backup job with Configuration Version 8.0.

If a VM has an older Configuration Version, will the older backup method still be used in Hyper-V 2016 and later environments?
Specifically, will the VSS of the Hyper-V Host be used as follows?
https://helpcenter.veeam.com/docs/backu ... nd-earlier

Is it possible to circumvent the host volume limitation by raising the Configuration Version to 8.0?
I want to back up the volumes of a Hyper-V host without splitting them.

I contacted the support team, but they said it was difficult to answer as it was due to Microsoft's specifications.
However, I was not satisfied with the support team's answer because the manual checkpointing operation was successful.
Case # 05190833

Kind Regards,
Asahi,
Climb inc.

[Mildur]

Hi

VSS has a limitation. VSS doesn't support more than 64TB Volume Size. And Veeam needs VSS to create backups.
I don't remember any workarounds, besides of designing the server to follow the guidelines of vss.

[Asahi]

Hi Mildur,

From the posts here, it seems that backups can be done even when the host volume exceeds 64TB.
microsoft-hyper-v-f25/64-tb-vss-snapsho ... 37419.html

Will VSS still be used on Hyper-V hosts when using Crash Consistent mode and in On-Host mode in Hyper-V 2016 and later?
https://helpcenter.veeam.com/docs/backu ... -and-later

From the user guide above, I thought VSS on Hyper-V hosts would not be used when in On-Host & Crash Consistent mode in Hyper-V 2016 or later.

Kind Regards,
Asahi,
Climb Inc.

[Mildur]

Then it should work without vss.
I must say, I don‘t have the experience with bigger servers than 15-20TB.

[Asahi]

Hi ,

Thank you for reply.

Looking at the backup log for Configuration Version 5.0, I found a mention of CTP.
This is a change detection method used in the backup method of Hyper-V 2012 R2 and earlier.
https://helpcenter.veeam.com/docs/backu ... #veeam-cbt

To use the RCT feature introduced in Hyper-V 2016, the Configuration Version must be 8.0.
https://helpcenter.veeam.com/docs/backu ... d-tracking

As mentioned in this forum post, I thought that using RCT = using the Hyper-V 2016 or later backup method would be a good way to get around the volume limitation.
microsoft-hyper-v-f25/64-tb-vss-snapsho ... 37419.html

My guess is that if the Configuration Version of the VM is 5.0, the entire backup process will be executed using the old (pre-Hyper-V 2012 R2) method even in Hyper-V 2016 or later environment.

Am I wrong in my thinking?
I wish someone would tell me.

Kind Regards,
Asahi,
Climb Inc.

[HannesK]

Hello,
did you already upgrade to version 8? Is it working now?

Thanks,
Hannes

[Asahi]

Hello Hannes,

I apologize for the delay in getting back to you.
I asked my customer to go to Ver8 and haven't heard from him yet.

Kind Regards,
Asahi,
Climb Inc.