Proxmox vs. XCP-ng: A Deep Dive into Open-Source Virtualization

The recent Broadcom-VMware virtualization licensing changes have made it necessary for many companies to re-evaluate their current setups. Proxmox VE is getting more and more traction as a well-known alternative, but there are also other great options, such as Xen-based XCP-ng, that offers a different approach to virtualization management.

Let’s examine Proxmox VE and XCP-ng to see how they compare in addressing today’s virtualization needs.

What Is Proxmox VE?

Proxmox VE is an open-source server virtualization platform based on Debian Linux. It goes beyond a simple hypervisor, offering a comprehensive solution for deploying and managing both virtual machines and containers. By utilizing KVM for full virtualization and Linux Containers (LXC) for lightweight virtualization, Proxmox VE provides great flexibility for sysadmins and DevOps teams. From a single interface, you can manage clusters, networks, hypervisor nodes, and backups. Also, one of standout features in Proxmox is its built-in Ceph distributed storage integration.

Key Proxmox VE Features:

• Web-Based Management: Proxmox VE web interface is designed for ease of use, making it accessible even to those new to virtualization.
• High Availability: Proxmox HA features use a quorum-based system, meaning a majority of nodes must be online for the cluster to function. This prevents “split-brain” scenarios where cluster nodes lose communication and start acting independently.
• Live Migration: This feature is crucial for minimizing downtime during maintenance. For instance, you can move a critical database VM to another host without interrupting service.
• Integrated Backup/Restore: Proxmox Backup Server is a native backup management software, that supports various storage backends, including NFS, CIFS, and local directories.
• Ceph Integration: Ceph is a distributed storage system that supports block, file, and object storage protocols and provides excellent scalability and redundancy.
• Software-Defined Networking: Proxmox SDN capabilities allow you to create complex network topologies.

What Is XCP-ng?

Born from a community effort in 2018, XCP-ng is a powerful virtualization platform built on the Xen hypervisor. You might recognize its lineage – it’s a direct descendant of Citrix XenServer. When Citrix shifted away from a fully open-source model, the community stepped in, reviving and enhancing the project as XCP-ng. This dedication to open-source principles has resulted in a stable, secure, and scalable virtualization solution. Notably, XCP-ng is now a proud member of the Linux Foundation through the Xen Project.

Key Features:

• Xen Hypervisor: Xen’s architecture provides strong isolation between VMs, which is crucial for security-sensitive applications.
• Xen Orchestra (XO): XO is a powerful web-based management interface that provides detailed insights into your virtual environment.
• Live Migration: XCP-ng’s live migration is highly efficient, allowing you to move VMs with minimal downtime.
• GPU Passthrough: This feature is essential for applications that require direct access to a GPU.
• Storage Management: XCP-ng supports various storage protocols, including NFS and iSCSI.

Key Differences Between Proxmox VE and XCP-ng

Choosing the right virtualization platform can significantly impact your infrastructure’s efficiency and performance. Here are key differences:

Performance: Proxmox vs. XCP-ng

Alright, so when people start comparing Proxmox and XCP-ng in terms of performance, the discussion usually gets pretty heated. Some swear by KVM’s efficiency, while others will tell you Xen’s microkernel design is just fundamentally better. Truth is, it all depends on what you’re running, how you’re running it, and what trade-offs you’re willing to make.

CPU and Memory

Now, both hypervisors handle CPU and memory allocation well – no major complaints there. But where things get interesting is how they handle it. Proxmox, built on KVM, relies on the Linux kernel for scheduling and memory management, making it feel more like a natural extension of a standard Linux system. Such tight integration is one reason why KVM has gained widespread adoption – it’s well-maintained, gets frequent updates, and benefits from improvements made across the Linux ecosystem.

XCP-ng, powered by Xen, takes a different approach. As a microkernel hypervisor, Xen isolates the control domain (dom0) from the guest VMs, handling CPU scheduling and memory management independently of the host OS. One advantage of this approach is better control over CPU feature exposure – Xen can handle mixed CPU environments more gracefully, avoiding compatibility issues that can arise when migrating VMs across different processor generations. Xen’s architecture also enables more fine-grained memory isolation, which contributes to its strong security model.

Storage

Storage performance is always one of the biggest bottlenecks in virtualization, and both platforms have their strengths.

Proxmox offers built-in support for Ceph, iSCSI, and NVMe-oF, which gives it a solid edge when it comes to distributed storage setups. XCP-ng, while supporting various storage backends, still lacks official support for Ceph and ZFS (though many people use it anyway). NVMe-oF is expected in version 9, but for now, it’s something to consider.

Now, here’s where things get interesting. Xen’s secure design for inter-VM communication means that storage performance isn’t as straightforward as KVM’s “DMA everywhere” approach with VirtIO. In raw benchmarks, KVM might pull ahead in single-VM disk performance. But when you’re running a lot of VMs, Xen’s architecture scales surprisingly well, saturating NVMe storage efficiently across multiple instances. That’s something to think about when looking at real-world performance instead of just lab benchmarks.

Networking

On paper, both Proxmox and XCP-ng offer similar networking capabilities: NIC bonding, LACP, SR-IOV, and so on. But again, the difference comes down to design philosophy.

KVM’s VirtIO networking is optimized for speed but doesn’t put security front and center. Xen, on the other hand, treats inter-VM communication with a bit more caution, ensuring that even virtual machines on the same system don’t implicitly trust each other. This means Xen-based networking can be ever so slightly slower in some cases, but it also reduces the attack surface. If you care more about raw throughput, KVM might have a slight edge, but if isolation and security are priorities, Xen is built with that in mind.

Key Takeaway

At the end of the day, the Proxmox vs. XCP-ng debate is less about which one is objectively better and more about what you actually need.

• Want bleeding-edge performance, faster updates, and wider industry adoption? Proxmox with KVM is probably the way to go.
• Care more about security, stability, and avoiding a Linux-only monoculture? XCP-ng and Xen might be worth your time.
• Storage-heavy workload? Single VM benchmarks favor KVM, but Xen scales better when running many VMs.

Neither is a bad choice, it all comes down to how much control you want, how much complexity you’re willing to deal with, and whether security or speed matters more in your setup. With VMware’s dominance fading, diversity in virtualization is more important than ever, and keeping options open might just be the smartest move.

Cost Analysis: Proxmox vs. XCP-ng

Both Proxmox VE and XCP-ng are open-source and free to use, with optional commercial support. However, there are key differences in how updates and support are structured.

Proxmox VE offers enterprise support subscriptions that provide access to stable, enterprise-grade repositories, security patches, and professional assistance. While Proxmox can be used without a subscription, users relying on the free version must use the “No-Subscription” repository, which may receive updates later than the enterprise repo.

XCP-ng, backed by Vates (the company behind Xen Orchestra), provides commercial support plans, but all users, free or paid, receive the same updates and patches. The difference is that paid customers get priority support, security hotfixes, and guaranteed SLAs.

Key Differences in Support Models:

• Proxmox restricts access to enterprise repositories for non-subscribers, while XCP-ng provides the same codebase and updates to everyone.
• XCP-ng’s commercial support is focused on enterprise-grade assistance and integrations, whereas Proxmox’s subscription model also affects update access.
• Proxmox benefits from Red Hat’s broader KVM ecosystem, while XCP-ng maintains an independent development roadmap for Xen.

For detailed pricing and support options:

• Proxmox VE pricing: https://www.proxmox.com/en/products/proxmox-virtual-environment/pricing
• Vates/XCP-ng pricing: https://vates.tech/pricing-and-support

How to Choose Between Proxmox and XCP-ng?

Choosing between Proxmox VE and XCP-ng isn’t about finding the “better” platform, it’s about finding the right fit for your unique setup. Both are powerful open-source virtualization platforms, but they approach performance, updates, security, and scalability differently.

Key Factors to Consider:

Infrastructure Compatibility

• If you require built-in Ceph, ZFS, or highly flexible storage options, Proxmox is a strong contender.
• For environments prioritizing security and VM isolation, XCP-ng’s design shines.

Technical Familiarity

• If you’re comfortable with Debian/Linux environments, Proxmox will feel intuitive.
• Those familiar with XenServer will find XCP-ng a seamless transition.

Update and Support Philosophy

• Proxmox emphasizes rapid development, with frequent updates, particularly for subscription users.
• XCP-ng prioritizes stability and predictability, making it ideal for environments where consistency is crucial.

Scalability and Future-Proofing

• For hyperconverged setups with deep storage integration, Proxmox is a more robust choice.
• XCP-ng’s Xen-based architecture offers superior isolation and long-term stability for multi-tenant, security-focused environments.

The Bigger Picture

With VMware’s dominance fading, keeping virtualization options open is more important than ever. Whether performance, security, or long-term ecosystem support matters most to you will ultimately decide which platform makes the most sense for your workload.