No need to run XM commands, it's enough to resize the LVM volume in dom0, and domU will pick up the change automatically (assuming both dom0 and domU kernels have the online resize feature included).

Great post! Many people don't seem to realize a lot has changed in the Xen-land during the last couple of years.. Xen dom0 support is now included in the upstream Linux kernel, and Xen developers are at the moment actively working on upstreaming for example qemu-xen to upstream Qemu. And for people who don't want to "do-it-yourself" there's Xen Cloud Platform (XCP) available.. opensource dedicated virtualization platform shipped as installable ISO image. http://xen.org/products/cloudxen.html .

Actually Xen is far from dead. Development is very active, and most of the important kernel-related patches have been upstreamed and included to Linux, including the much discussed Xen Dom0 support. So the situation nowadays is very different from a couple of years back.

truecolor framebuffers have been supported for many years in Xen. You can install either PV or HVM VMs using truecolor graphics. In the case of PV domU you need to use 'vfb' or 'pvfb', aka paravirtual framebuffer. Framebuffers are exposed as VNC servers, or over SDL.

Xen online resizing of VM disks has been supported for a while already! You just need to use a kernel that supports it. Online resizing is supported in mainline upstream Linux as of 2.6.37 (iirc), and some distros have backported it older kernels.

Actually Xen dom0 support *IS* already in mainline upstream Linux kernel as of 2.6.37 ! Some xen backend drivers are still missing from upstream kernel, but upcoming Linux 2.6.39 includes xen-netback backend driver, and xen-blkback driver is planned for 2.6.40. http://blog.xen.org/index.php/2011/01/14/linux-2-6-37-first-upstream-linux-kernel-to-work-as-dom0/ The pvops framework was merged to Linux 2.6.24 a couple of years ago, and Xen pvops domU support was first usable in Linux 2.6.26. So Xen support has been in upstream Linux kernel for 12 major kernel releases already! Also Redhat RHEL6 runs as Xen VM, both PV and HVM, just as pretty much any distro does nowadays. Upcoming Fedora 15 has a Xen dom0 capable kernel, and it is expected that Fedora 16 will have fully featured Xen dom0 support out-of-the-box (including all the backend drivers that are being upstreamed atm).

Xen dom0 patches are available for 2.6.27, 2.6.29, 2.6.31, 2.6.32, 2.6.33 etc..most people prefer 2.6.32 atm, since that's the long-term maintained kernel from both kernel.org and xen.org. For more information: http://wiki.xensource.com/xenwiki/XenDom0Kernels . Xen developers are also busy preparing (and rewriting) the Xen dom0 support for the mainline Linux Xen pvops framework, which has been in upstream Linux since 2.6.24.

RHEL5 will fully support Xen until 2014 (which is when RHEL5 goes EOL). Redhat has stated this multiple times. Also upcoming RHEL6 runs as Xen guest, on RHEL5 Xen host/dom0. So there's no need to switch away from Xen.

From the new enterprise distributions Suse Linux Enterprise 11 (SLES11) SP1 fully supports Xen, including the new Xen 4.0 hypervisor, and Linux 2.6.32 based dom0 kernel. OpenSUSE also has Xen included/supported. Upcoming Debian 6.0 ("Squeeze") will also have Xen (including dom0).

This has changed pretty much lately. A lot of new documentation has been written to the wiki, for example: http://wiki.xensource.com/xenwiki/XenCommonProblems has a lot of stuff and links to other new documentation pages. Have you heard of XCP (Xen Cloud Platform, http://www.xen.org/products/cloudxen.html)? It's a full "Xen distribution" featuring install CD, including everything needed for multi-host/pool management. No need to install custom kernels or anything. You can use OpenXenCenter (http://www.openxencenter.com/) to manage it, if you need a GUI tool.

RHEL6 will support running as Xen guest, both PV and HVM. You can use RHEL5 as the Xen host (dom0), and run RHEL6 guests on it.

Did you try XCP (Xen Cloud Platform, http://www.xen.org/products/cloudxen.html) ? XCP 0.5 is coming out in June.. you can manage it using OpenXenCenter (http://www.openxencenter.com). Basicly XCP is XenServer opensourced and developer further..

I think that has been already supported for a while in Xen..

Fedora 13 contains Xen hypervisor and tools, but it doesn't contain rpm package for a Xen dom0 capable kernel. There are unofficial Fedora rpm packages for a Xen dom0 capable kernel, based on the upstream pvops dom0 kernels (Linux 2.6.32). More information about Fedora Xen status and links to rpms see: http://fedoraproject.org/wiki/Features/XenPvopsDom0 . More information about available Xen dom0 kernel options see: http://wiki.xensource.com/xenwiki/XenDom0Kernels .

Some comments.. Xen hypervisor (xen.gz) is not meant to be integrated to Linux kernel. Xen is designed to be a separate piece of software. Xen is a secure, type-1 baremetal hypervisor, not a module for Linux. Xen dom0 ("service console") can be Linux, NetBSD or OpenSolaris. Most people use Linux as Xen dom0. When Linux is used as dom0 it needs to be able to run as Xen dom0 (obviously) - and this is where some people have had pain. For a long time the official Xen dom0 kernel patches were only available for Linux 2.6.18. This was difficult for many people and caused some distros to drop Xen dom0 kernel support because they couldn't affort porting the patches to newer kernels themselves. Today the situation is different. Xen developers are actively working on rewriting the Xen dom0 patches based on the (already existing) upstream pvops framework. pvops has been in the upstream Linux kernel since 2.6.24. Xen pvops dom0 patches are available today for the long-term maintained 2.6.32 kernel, and also for 2.6.31, 2.6.33 and 2.6.34. Novell has also forward-ported the old/traditional Xenlinux patches from 2.6.18 to first 2.6.27 and also to 2.6.31, 2.6.32 and 2.6.33. So there are many options today. For more information about the various Xen dom0 kernels see: http://wiki.xensource.com/xenwiki/XenDom0Kernels Also xen.org offers XCP (Xen Cloud Platform) which is a full platform, including installation CD and multi-host/pool management. If you use XCP you don't need to install custom kernels or anything - you get all included in the XCP bundle. More information about XCP: http://www.xen.org/products/cloudxen.html