In-place upgrade to Windows Server 2025

[adam900331]

Hy!

I have a phisycal server with Windows Server 2019. This server has all of the role like, backup server, tape server (direct connected a tape library), mount server, etc. The Backup for M365 software is also run on this phisycal server. I am planning to run in-place upgrade to install the Window Server 2025. What is worth paying attention to? What are the prerequisites for an in-place upgrade?

[Mildur]

Hi Adam,

We don’t officially test in-place upgrades, so we can’t guarantee the outcome or provide prerequisites.
If you decide to proceed anyway, make sure you have a copy of your backups on a second repository and a configuration backup, just in case.

One important note: If your backup server also acts as a ReFS backup repository, please review our KB for common ReFS issues (KB2792). We strongly advise against in-place OS upgrades of ReFS-based Windows repository servers.

Windows Repository Server Upgrades
There have been instances where customers reported data loss after performing an in-place OS upgrade on a Windows Server hosting an ReFS volume that acts as a Windows Repository. The issue arises when the OS attempts to upgrade the ReFS version of the volume and the process fails. For this reason, Veeam strongly advises against performing in-place OS upgrades for ReFS-based Windows Repositories.

Best,
Fabian

[adam900331]

Hy Fabian!

We use ReFS file system for store backups. In short, do I have to move the existing backup data to another place and after the upgrade, format the original repository and copy back to the original location?

[Mildur]

That will protect your backups from getting corrupted, yes. However, I strongly recommend using Veeam Mover instead of Windows built-in tools. Moving backup files with Windows Explorer (or similar tools) is not block-clone aware.

If you’re already considering moving backups to different disks during the upgrade, another option would be to deploy a new Veeam Backup & Replication v13 server using the Veeam Software Appliance (VM), move all backups to a temporary repository, then redeploy your current backup server as a Linux Hardened Repository (using the Veeam Infrastructure ISO) and move the backups back. Create new backup jobs and mount them to the migrated backups.

Benefits: no Windows in-place upgrades anymore, and you get immutable backups.

Best,
Fabian