Look, it’s quite easy to pooh-pooh them trying to improve the performance of their OS on Windows’ virtualisation. At the end of the day, if there aren’t people who want the product, they won’t make much out of it, and if there are people who want it I don’t see what the harm is. If people want to run Windows to virtualise servers, if the free software performance sucks they’re just going to run more Windows.

I’m starting to see others who frown upon Microsoft+Novell:

http://news.cnet.com/8301-13846_3-10039172-62.html

“As Suse Linux fades further from any relevance outside of Microsoft, and Red Hat and Sun make huge strides in virtualization, Novell plans to offer support for Suse running on Windows. Is there meaning here or is Novell just becoming more of a Microsoft puppet?”

In terms of free software competitors, it’s actually something like oVirt which is the competitor: and in that sense, it doesn’t matter if it’s KVM, Xen, or some other system – with a single virtualisation API you don’t really “care” any more because they all look the same. You just pick the appropriate one for your hardware and/or software and/or other needs.

KVM is in the mainline kernel because it’s a simple solution given the hardware support. Xen exists to provide support where hardware isn’t available. They’re different solutions for different jobs, and KVM is still quite immature.

The truth about KVM and Xen

When the distros first shipped Xen, it was done mostly out of desperation. Virtualization was, and still is, the “hot” thing. Linux did not provide any native hypervisor capability. Most Linux developers didn’t even really know that much about virtualization. Xen was a pretty easy to use purpose-built kernel that had a pretty good community. So we made the hasty decision to ship Xen instead of investing in making Linux a proper hypervisor.

This decision has come back to haunt us now in the form of massive confusion. When people talk about Xen not being merged into Linux, I don’t think they realize that Xen will never be merged into Linux. Xen will always be a separate, purpose-built kernel. There are patches to Linux that enable it to run well as a guest under Xen. These patches are likely to be merged in the future, but Xen will never been a part of the Linux kernel.

[...]

Looking at the rest of the industry, I’m surprised that other kernels haven’t gone in the direction of Linux in terms of adding hypervisor support directly to the kernel.

Why is Windows not good enough to act a hypervisor such that Microsoft had to write a new kernel from scratch (Hyper-V)?

Why is Solaris not good enough to act as a hypervisor requiring Sun to ship Xen in xVM? Solaris is good enough to run enterprise workloads but not good enough to run a Windows VM? Really? Maybe

Forget about all of the “true hypervisor” FUD you may read. The real question to ask yourself is what is so wrong with these other kernels that they aren’t capable of running virtual machines well and instead have to rely on a relatively young and untested microkernel to do their heavy lifting?

KVM and Xen cofounders engage in war of words

Maybe, but Pratt was responding to his KVM?s competitors? claims that Xen’s days are numbered because of KVM?s tight integration with the Linux kernel.

Increasing Virtualization Insanity

For sysadmin types this means: do what you have to do with Xen for now. But keep the investments small. For developers this means: don’t let yourself be tied to a platform. Use an abstraction layer such as libvirt to bridge over the differences. For architects this means: don’t looking to Xen for answers, base your new designs on KVM.

Xen vs. KVM: round 1 bell to ring soon

Industry executives are downplaying concerns about a growing schism between rival open source virtualization factions but a market battle between Xen and KVM appears increasingly likely, and imminent.

Linux: KVM Adds Support For SMP Guests

A recently merged KVM patchset included support for guest SMP, various performance improvements, and suspend/resume fixes. KVM stands for Kernel-based Virtual Machine,

Linux: Improved KVM Performance, Vista Support

Avi Kivity announced significant performance improvements and support for running 32-bit Windows Vista as a guest within the latest release of KVM.

Linux KVM Virtualization Performance

The benefits of KVM are high performance, stable, no modifications of the guest operating system are necessary, and a great deal of other capabilities (e.g. using the Linux scheduler). Once the Linux 2.6.20 kernel is officially out the door we will proceed with a greater number of KVM benchmarks in various environments including looking at the hardware virtualization performance between AMD and Intel.