Proxmox in business: why I virtualise new servers with it

When a client needs new servers, I now plan the virtualisation with Proxmox VE as a rule. That applies to new hardware as much as to environments that have so far run on VMware or Hyper-V. This article explains why I make that choice, how I set up backup and resilience, what to bear in mind with Windows Server, and when I stay with the existing platform after all. It is based on projects from 2024 and 2025.

Why Proxmox became my standard

Proxmox VE is an open-source virtualisation platform based on Debian. It manages virtual machines and containers through a web interface and comes with clustering, high availability and its own backup solution. For the environments I look after, typically one to three hosts running a domain controller, file services, line-of-business applications and a handful of other servers, it covers everything that is needed.

Three things decide it for me. The platform is economical for small environments, also since VMware changed its licensing model. It is openly documented, so another provider or your in-house IT can carry on working with it. And virtualisation and backup come from the same source and fit together cleanly.

Moving from VMware or Hyper-V

I have done both with clients. Since version 8.2, Proxmox VE includes an import wizard that takes virtual machines directly from an ESXi host and carries over most of their configuration. Hyper-V machines are converted and imported via their disk files. In both cases the transfer itself is rarely the hard part.

The effort lies in the preparation. Windows systems need the VirtIO drivers so that disks and network run at full speed. Licences tied to hardware characteristics may need to be activated again. And for every machine I clarify beforehand how long it may be down and in which order the services have to come back up.

A single host or a cluster?

That depends on how long an outage may last. A single host with good backups is enough for many small companies: if it fails, the machines are restored from backup. Where that takes too long, I set Proxmox up as a cluster of several hosts. Virtual machines can then be moved while running, for maintenance for example, and restarted on another host if the hardware fails.

For a cluster with automatic high availability, Proxmox recommends at least three nodes, so that the majority vote still works when one host is down. With two hosts, a small additional device provides that third vote.

Backup in two stages

For backups I use Proxmox Backup Server. I deliberately keep the first stage close to the host: the nightly backup runs locally, finishes very quickly and puts hardly any load on the server. Because the backup server only stores changed data blocks, storage requirements stay manageable too.

A local backup on its own does not protect against hardware failure, fire or an attack that reaches the host. So every backup is transferred in a second stage to external storage or a second backup server. This synchronisation can happen over the following day, including during business hours. I limit the bandwidth for each sync job, so nobody in the office notices.

For the off-site copy I offer a managed backup on my own servers in German data centres. This copy is separated from the client’s network, and permissions are limited in both directions. The backup system in the data centre pulls the data itself and has read-only access to the client network. In turn, the client system has no write access to the backup system. If either side is compromised, it cannot change, delete or encrypt data on the other.

Windows Server on Proxmox

This question comes up almost every time. The short answer: Windows Server runs on Proxmox, and at my clients it runs that way without restrictions.

• Licensing: Windows Server Standard and Datacenter are licensed by the physical cores of the host, whatever virtualisation runs on it. Each server needs at least 16 core licences. Standard edition allows two virtual Windows servers on a fully licensed host. If you move machines between hosts in a cluster, clarify beforehand which hosts need to be licensed for that.
• Support: Proxmox is not one of the platforms with which Microsoft has a joint support agreement. Microsoft does not officially test its software there. For customers with Premier support, Microsoft will still investigate, but may require a fault to be reproduced under Hyper-V or on physical hardware first. For small environments without such a contract this rarely matters, but I point it out in advance.
• Technology: VirtIO drivers, the QEMU guest agent and suitable processor and disk settings are part of the basic setup. Proxmox documents its own recommendations for Windows guests.

When I stay with the existing platform

It is rare, but it happens. If a company has an in-house IT team that works with VMware or Hyper-V every day and has the environment firmly under control, that knowledge often outweighs the benefits of switching. A platform your own team does not know is the worse choice when something goes wrong. In those cases I recommend staying put and look after backup, updates and documentation instead.

Sources

• Import wizard for VMware ESXi: Proxmox – Proxmox Virtual Environment 8.2 with Import Wizard released
• Moving from VMware and Hyper-V: Proxmox VE Wiki – Migrate to Proxmox VE
• Cluster and quorum: Proxmox VE documentation – Cluster Manager
• Sync and bandwidth limits: Proxmox Backup Server – Managing Remotes & Sync
• Windows guests: Proxmox VE Wiki – Windows 2022 guest best practices
• Windows Server licensing: Microsoft – Windows Server 2025 Licensing Guidance
• Support on other virtualisation platforms: Microsoft Learn – Support policy for Microsoft software that runs on non-Microsoft hardware virtualization software