[RealStickman_]

This made me curious to find out reasons why KVM is so much more popular than Xen. I wasn't able to find anything concrete beyond "KVM is the standard and supported by out tooling", which obviously is the case nowadays, but still leaves me wondering what KVM did so much better than Xen when it first released or if this was just a concidence.

[shortsunblack]

KVM was made because Citrix made moves against Xen that spooked Linux community, hence KVM. Then Red Hat ran with it and based its virtualization platform on it.

Citrix involvement has subsided in meantime and the ecosystem is much healthier (governance is actually under Linux Foundation), but the damage was done.

Xen to this day lacks in features, also.

[jacobgorm]

Also, Xen's main clame to fame was that para-virtualization allowed it to host Linux and *BSD VMs at close to zero overhead, but at time what everyone was looking for was a way to host Windows VMs, which is where all the pain points and the money was. CPUs were evolving to support this use-case, making para-virtualization less important, and Xen had to evolve quite quickly to include QEMU in the mix, leaving a bit of convoluted mess initially, and causing a lot of friction during the attempts to get merged into the Linux kernel. On top, the Xen management tool-stack had been written by happy amateurs in Python and Twisted, before any of those technologies where near ready for production use, with massive slowness and unfixable memory leaks as results. KVM provided a fresh take built with the benefits of hindsight, got merged into Linux on the first attempt, and gained the backing of Redhat, and the rest is more of less history.

[jacobgorm]

KVM was launched before Citrix acquired XenSource. But Redhat had also tried to acquire XenSource and threatened its founders that if they did not come along Redhat would “rip off their heads and shit down the hole”, because “Redhat was the only company allowed to make money off open source”. In that light it made sense for Redhat to back a competitor to Xen.

[rickydroll]

The Citrix fuckery triggered the development of XCP-ng. I've been using the XCP-ng/Xen Orchestra stack for several years now, both in my homelab and professionally. It is so much easier to work with than KVM that it's part of my go-to toolkit.

If you have a spare machine or feel like picking up a tiny form factor i5 PC, you can play with Zen and Xen Orchestra fairly easily.

I once ran a three-node cluster of TinyFormFactor PCs running Xen, and it was A good framework for learning. The only reason I moved away from it is that the TFF PCs only had one gigabit Ethernet port and were limited to 32GB of RAM. I moved to more traditional small desktop PCs so I could add multiple 10-gigabit Ethernet interfaces and RAM.

Someday, I'll write up how I did an easy DMZ with XCP-ng.

[RealStickman_]

I use and like XCP-ng in my homelab, but the initial release was apparently in 2018. That's still ~15 years of Citrix fuckery that apparently birthed KVM.

[rickydroll]

Yeah, Citrix really made a mess of things. If you look at the history of IT companies, it's impressive how many user/company decisions are made because of vendor fuckery.