[libvirt-users] migrating from XenServer / XCP to libvirt/KVM

I've been using XenServer / XCP (with the "xe" toolset) for a number of years for hosting servers used for development and free software projects and I'm now looking at migrating all those environments to libvirt / KVM. I had a look at the wiki[1] already and didn't see XenServer mentioned there. Could anybody help comment on or explain a few things: - comparison between XenServer and libvirt: I notice many similar concepts, for example, XenServer has storage repositories and libvirt has storage pools. However, in many examples such as this[2] it appears that libvirt requires more manual effort. For example, when you create a storage repository in XenServer, the tool takes a physical block device as input and creates the necessary volume group, logical volume and a filesystem. In that libvirt example, it appears each of those steps must be done manually. The networking examples are similar: the XenServer tools do all the Open vSwitch stuff behind the scenes but in the libvirt examples it appears necessary to create the bridge manually before telling libvirt about it. Is this all correct or are the examples I've seen out of date? Do more recent (or future) releases of libvirt aim to automate/hide more of these things? - what is best practice for virtual disk images? Does libvirt always use files (like XenServer) or can/should block devices be used directly? If using files, is any special care needed to avoid block alignment problems? - are there any guides or tools recommended for migrating small XenServer environments (less than 50 domains on a single physical node) to libvirt + KVM? - is there a list of small things that need to change in a VM before running it under libvirt / KVM? I'm guessing this might include bootloader config, updating the kernel, changing block device names in /etc/fstab and changing network device names in scripts - are there any others? - can anybody comment on more tricky issues that may arise in such a migration, for example, will a Windows VM be likely to run without modification when migrated from XenServer to libvirt/KVM or will it need extra drivers added or anything else before the migration? Regards, Daniel 1. http://wiki.libvirt.org/page/Main_Page 2. https://keepingitclassless.net/2014/01/libvirt-intro-basic-configuration/