Xen to KVM Migration Guide #

This section contains information to help you import virtual machines from foreign hypervisors (such as Xen) to KVM managed by libvirt.

Tip: Microsoft Windows Guests

This section is focused on converting Linux guests. Converting Microsoft Windows guests using virt-v2v is the same as converting Linux guests, except in regards to handling the Virtual Machine Driver Pack (VMDP). Additional details on converting Windows guests with the VMDP can be found in the separate Virtual Machine Driver Pack documentation at https://documentation.suse.com/sle-vmdp/.

sudo zypper install virt-v2v

1.3 Preparing the Virtual Machine #

 

Note: Conditions for Skipping This Step

If running virt-v2v on SLES 12 SP1 or before, this step can be safely skipped. This step can also be ignored if the virtual machine is fully virtualized or if it runs on SLES 12 SP2 or later.

The Xen virtual machine must have default kernel installed. To ensure this, run zypper in kernel-default on the virtual machine.

1.4 Converting Virtual Machines to Run under KVM Managed by libvirt #

 

virt-v2v converts virtual machines from the Xen hypervisor to run under KVM managed by libvirt. To learn more about libvirt and virsh, see Part II, “Managing Virtual Machines with libvirt”. Additionally, all virt-v2v command line options are explained in the virt-v2v manual page (man 1 virt-v2v).

Before converting a virtual machine, make sure to complete the following steps:

Procedure 1: Preparing the Environment for the Conversion #

 

1. Create a new local storage pool.

   virt-v2v copies the storage of the source virtual machine to a local storage pool managed by libvirt (the original disk image remains unchanged). You can create the pool either with Virtual Machine Manager, or virsh. For more information, see Section 12.1, “Managing Storage with Virtual Machine Manager” and Section 12.2, “Managing Storage with virsh”.

2. Prepare the local network interface.

   Check that the converted virtual machine can use a local network interface on the VM Host Server. It is usually a network bridge. If it is not defined yet, create it with YaST › System › Network Settings › Add › Bridge.

   

   Note: Mappings of Network Devices

   Network devices on the source Xen host can be mapped during the conversion process to corresponding network devices on the KVM target host. For example, the Xen bridge br0 can be mapped to the KVM network default. Sample mappings can be found in /etc/virt-v2v.conf. To enable these mappings, modify the XML rule as necessary and ensure the section is not commented out with <!-- and --> markers. For example:

    <network type='bridge' name='br0'>
      <network type='network' name='default'/>
    </network>

   

   Tip: No Network Bridge

   If there is no network bridge available, Virtual Machine Manager can optionally create it.

virt-v2v has the following basic command syntax:

virt-v2v -i INPUT_METHOD -os STORAGE_POOL SOURCE_VM

input_method

There are two input methods: libvirt or libvirtxml. See the SOURCE_VM parameter for more information.

storage_pool

The storage pool you already prepared for the target virtual machine.

source_vm

The source virtual machine to convert. It depends on the INPUT_METHOD parameter: For libvirt, specify the name of a libvirt domain. For libvirtxml, specify the path to an XML file containing a libvirt domain specification.

Note: Conversion Time

Conversion of a virtual machine takes a lot of system resources, mainly for copying the whole disk image for a virtual machine. Converting a single virtual machine typically takes up to 10 minutes, although virtual machines using very large disk images can take much longer.

1.4.1 Conversion Based on the libvirt XML Description File #

 

This section describes how to convert a local Xen virtual machine using the libvirt XML configuration file. This method is suitable if the host is already running the KVM hypervisor. Make sure that the libvirt XML file of the source virtual machine, and the libvirt storage pool referenced from it are available on the local host.

1. Obtain the libvirt XML description of the source virtual machine.

   

   Tip: Obtaining the XML Files

   To obtain the libvirt XML files of the source virtual machine, you must run the host OS under the Xen kernel. If you already rebooted the host to the KVM-enabled environment, reboot back to the Xen kernel, dump the libvirt XML file, and then reboot back to the KVM environment.

   First identify the source virtual machine under virsh:

   root # virsh list
    Id    Name                           State
   ----------------------------------------------------
   [...]
     2     sles12_xen                     running
   [...]

   sles12_xen is the source virtual machine to convert. Now export its XML and save it to sles12_xen.xml:

   root # virsh dumpxml sles12_xen > sles12_xen.xml

2. Verify all disk image paths are correct from the KVM host's perspective. This is not a problem when converting on one machine, but may require manual changes when converting using an XML dump from another host.

   <source file='/var/lib/libvirt/images/XenPool/SLES.qcow2'/>

   

   Tip: Copying Images

   To avoid copying an image twice, manually copy the disk image(s) directly to the libvirt storage pool. Update the source file entries in the XML description file. The virt-v2v process will detect the existing disks and convert them in place.

3. Run virt-v2v to convert to KVM virtual machine:

   root # virt-v2v sles12_xen.xml1 \
   -i LIBVIRTXML2 \
   -os remote_host.example.com:/exported_dir3 \
   --bridge br04 \
   -on sles12_kvm5

   1	The XML description of the source Xen-based virtual machine.
   2	virt-v2v will read the information about the source virtual machine form a libvirt XML file.
   3	Storage pool where the target virtual machine disk image will be placed. In this example, the image will be placed on an NFS share /exported_dir on the remote_host.example.com server.
   4	The target KVM-based virtual machine will use the network bridge br0 on the host.
   5	The target virtual machine will be renamed to sles12_kvm to prevent name collision with the existing virtual machine of the same name.

1.4.2 Conversion Based on the libvirt Domain Name #

 

This method is useful if you are still running libvirt under Xen, and plan to reboot to the KVM hypervisor later.

1. Find the libvirt domain name of the virtual machine you want to convert.

   root # virsh list
    Id    Name                           State
   ----------------------------------------------------
   [...]
     2     sles12_xen                     running
   [...]

   sles12_xen is the source virtual machine to convert.

2. Run virt-v2v to convert to KVM virtual machine:

   root # virt-v2v sles12_xen1 \
   -i libvirt2 \
   -os storage_pool3 \
   --network eth04 \
   -of qcow25 \
   -oa sparce6 \
   -on sles12_kvm

   1	The domain name of the Xen-based virtual machine.
   2	virt-v2v will read the information about the source virtual machine directly from the active libvirt connection.
   3	The target disk image will be placed in a local libvirt storage pool.
   4	All guest bridges (or networks) will be connected to a locally managed network.
   5	Format for the disk image of the target virtual machine. Supported options are raw or qcow2.
   6	If the converted guest disk space will be sparse or preallocated.

1.4.3 Converting a Remote Xen Virtual Machine #

 

This method is useful if you need to convert a Xen virtual machine running on a remote host. As virt-v2v connects to the remote host via ssh, ensure that SSH service is running on the host.

Note: Passwordless SSH Access

Starting with SLES 12 SP2, virt-v2v requires a passwordless SSH connection to the remote host. This means a connection using an SSH key added to the ssh-agent. See man ssh-keygen and man ssh-add for more details on this.

To connect to a remote libvirt connection, construct a valid connection URI relevant for your remote host. In the following example, the remote host name is remote_host.example.com, and the user name for the connection is root. The connection URI then looks as follows:

xen+ssh://root@remote_host.example.com/

For more information on libvirt connection URIs, see https://libvirt.org/uri.html.

1. Find the libvirt domain name of the remote virtual machine you want to convert.

   root # virsh -c xen+ssh://root@remote_host.example.com/ list
    Id    Name                           State
   ----------------------------------------------------
     1     sles12_xen                     running
   [...]

   sles12_xen is the source virtual machine to convert.

2. The virt-v2v command for the remote connection looks like this:

   root # virt-v2v sles12_xen \
   -i libvirt \
   -ic xen+ssh://root@remote_host.example.com/ \
   -os local_storage_pool \
   --bridge br0

1.5 Running Converted Virtual Machines #

 

After virt-v2v completes successfully, a new libvirt domain will be created with the name specified with the -on option. If you did not specify -on, the same name as the source virtual machine will be used. The new guest can be managed with standard libvirt tools, such as virsh or Virtual Machine Manager.

Tip: Rebooting the Machine

If you completed the conversion under Xen as described in Section 1.4.2, “Conversion Based on the libvirt Domain Name”, you may need to reboot the host machine and boot with the non-Xen kernel.

For more information on libvirt, see https://libvirt.org.

You can find more details on libvirt XML format at https://libvirt.org/formatdomain.html.

For more information on virtualization with Xen and KVM, see the SUSE Linux Enterprise Server documentation at http://www.suse.com/doc/.

This section lists content changes for this document.

Copyright© 2006– 2024 SUSE LLC e colaboradores. Todos os direitos reservados.

Permissão concedida para copiar, distribuir e/ou modificar este documento sob os termos da Licença GNU de Documentação Livre, Versão 1.2 ou (por sua opção) versão 1.3; com a Seção Invariante sendo estas informações de copyright e a licença. Uma cópia da versão 1.2 da licença está incluída na seção intitulada “GNU Free Documentation License” (Licença GNU de Documentação Livre).

Para ver as marcas registradas da SUSE, visite http://www.suse.com/company/legal/. Todas as marcas comerciais de terceiros pertencem a seus respectivos proprietários. Os símbolos de marca registrada (®,™ etc.) representam marcas registradas da SUSE e suas afiliadas. Os asteriscos (*) indicam marcas registradas de terceiros.

Todas as informações deste manual foram compiladas com a maior atenção possível aos detalhes. Entretanto, isso não garante uma precisão absoluta. A SUSE LLC, suas afiliadas, os autores ou tradutores não serão responsáveis por possíveis erros nem pelas consequências resultantes de tais erros.

Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc. 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

The purpose of this License is to make a manual, textbook, or other functional and useful document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or non-commercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

We have designed this License to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you". You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.

A "Modified Version" of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

A "Secondary Section" is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document's overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

The "Invariant Sections" are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.

The "Cover Texts" are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.

A "Transparent" copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not "Transparent" is called "Opaque".

Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only.

The "Title Page" means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, "Title Page" means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text.

A section "Entitled XYZ" means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as "Acknowledgements", "Dedications", "Endorsements", or "History".) To "Preserve the Title" of such a section when you modify the Document means that it remains a section "Entitled XYZ" according to this definition.

The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.

You may copy and distribute the Document in any medium, either commercially or non-commercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.

You may also lend copies, under the same conditions stated above, and you may publicly display copies.

If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document's license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles.

You may add a section Entitled "Endorsements", provided it contains nothing but endorsements of your Modified Version by various parties--for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.

You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.

The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections Entitled "History" in the various original documents, forming one section Entitled "History"; likewise combine any sections Entitled "Acknowledgements", and any sections Entitled "Dedications". You must delete all sections Entitled "Endorsements".

You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an "aggregate" if the copyright resulting from the compilation is not used to limit the legal rights of the compilation's users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document's Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.

Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.

If a section in the Document is Entitled "Acknowledgements", "Dedications", or "History", the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.

You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.

The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See https://www.gnu.org/copyleft/.

Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation.

Copyright (c) YEAR YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
A copy of the license is included in the section entitled “GNU
Free Documentation License”.

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with...Texts.” line with this:

with the Invariant Sections being LIST THEIR TITLES, with the
Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.

If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.