Your IP : 216.73.217.13
<!doctype html>
<html class="no-js" lang="en" data-content_root="../../">
<head><meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<meta name="color-scheme" content="light dark"><meta name="viewport" content="width=device-width, initial-scale=1" />
<meta property="og:title" content="VM live migration implementation" />
<meta property="og:type" content="website" />
<meta property="og:url" content="/reference/vm_live_migration_internals/" />
<meta property="og:site_name" content="LXD documentation" />
<meta property="og:description" content="Live migration in LXD is achieved by streaming instance state from a source QEMU to a target QEMU. VM live migration is supported for all storage pool types. API extension: migration_vm_live Concep..." />
<meta property="og:image" content="https://documentation.ubuntu.com/lxd/latest/_static/lxd_tag.png" />
<meta property="og:image:alt" content="LXD documentation" />
<meta name="description" content="Live migration in LXD is achieved by streaming instance state from a source QEMU to a target QEMU. VM live migration is supported for all storage pool types. API extension: migration_vm_live Concep..." />
<meta property="article:modified_time" content="2026-02-13T21:24:04+00:00" /><link rel="index" title="Index" href="../../genindex/"><link rel="search" title="Search" href="../../search/"><link rel="next" title="Dqlite internals" href="../dqlite-internals/"><link rel="prev" title="OVN implementation" href="../ovn-internals/">
<link rel="canonical" href="/reference/vm_live_migration_internals/">
<link rel="shortcut icon" href="../../_static/favicon.ico"><!-- Generated with Sphinx 7.4.7 and Furo 2025.12.19 -->
<title>VM live migration implementation - LXD documentation</title>
<link rel="stylesheet" type="text/css" href="../../_static/pygments.css?v=d111a655" />
<link rel="stylesheet" type="text/css" href="../../_static/styles/furo.css?v=7bdb33bb" />
<link rel="stylesheet" type="text/css" href="../../_static/copybutton.css?v=76b2166b" />
<link rel="stylesheet" type="text/css" href="../../_static/config-options.css" />
<link rel="stylesheet" type="text/css" href="../../_static/related-links.css" />
<link rel="stylesheet" type="text/css" href="../../_static/terminal.css" />
<link rel="stylesheet" type="text/css" href="../../_static/youtube.css" />
<link rel="stylesheet" type="text/css" href="../../_static/sphinx-design.min.css?v=95c83b7e" />
<link rel="stylesheet" type="text/css" href="../../_static/styles/furo-extensions.css?v=8dab3a3b" />
<link rel="stylesheet" type="text/css" href="../../_static/lxd_custom.css?v=bfbf4da2" />
<link rel="stylesheet" type="text/css" href="../../_static/cookie-banner.css?v=b74831ab" />
<link rel="stylesheet" type="text/css" href="../../_static/custom.css?v=e189117a" />
<link rel="stylesheet" type="text/css" href="../../_static/header.css?v=a8078839" />
<link rel="stylesheet" type="text/css" href="../../_static/github_issue_links.css?v=3d761185" />
<link rel="stylesheet" type="text/css" href="../../_static/furo_colors.css?v=825fec6f" />
</head>
<body>
<header id="header" class="p-navigation">
<!-- Google Tag Manager -->
<script>
(function(w, d, s, l, i) {
w[l] = w[l] || [];
w[l].push({
'gtm.start': new Date().getTime(),
event: 'gtm.js'
});
var f = d.getElementsByTagName(s)[0];
var j = d.createElement(s);
var dl = '';
if (l != 'dataLayer') {
dl = '&l=' + l;
}
j.async = true;
j.src = 'https://www.googletagmanager.com/gtm.js?id=' + i + dl;
f.parentNode.insertBefore(j, f);
})(window, document, 'script', 'dataLayer', 'GTM-KNX3CJC');
</script>
<div class="p-navigation__nav" role="menubar">
<ul class="p-navigation__links" role="menu">
<li>
<a class="p-logo" href="https://canonical.com/lxd" aria-current="page">
<img src="../../_static/lxd_tag.png" alt="Logo" class="p-logo-image">
<div class="p-logo-text p-heading--4">LXD
</div>
</a>
</li>
<li class="nav-ubuntu-com">
<a href="https://canonical.com/lxd" class="p-navigation__link">canonical.com/lxd</a>
</li>
<li class="nav-dropdown">
<a href="#" class="p-navigation__link nav-more-links"
id="more-resources-toggle"
aria-haspopup="true"
aria-expanded="false">
More resources
</a>
<ul class="more-links-dropdown" aria-labelledby="more-resources-toggle">
<li>
<a href="https://discourse.ubuntu.com/c/lxd/" class="p-navigation__sub-link p-dropdown__link">Discourse</a>
</li>
<li>
<a href="https://matrix.to/#/#documentation:ubuntu.com" class="p-navigation__sub-link p-dropdown__link">Matrix</a>
</li>
<li>
<a href="https://github.com/canonical/lxd" class="p-navigation__sub-link p-dropdown__link">GitHub</a>
</li>
</ul>
</li>
</ul>
</div>
</header>
<script>
document.body.dataset.theme = localStorage.getItem("theme") || "auto";
</script>
<svg xmlns="http://www.w3.org/2000/svg" style="display: none;">
<symbol id="svg-toc" viewBox="0 0 24 24">
<title>Contents</title>
<svg stroke="currentColor" fill="currentColor" stroke-width="0" viewBox="0 0 1024 1024">
<path d="M408 442h480c4.4 0 8-3.6 8-8v-56c0-4.4-3.6-8-8-8H408c-4.4 0-8 3.6-8 8v56c0 4.4 3.6 8 8 8zm-8 204c0 4.4 3.6 8 8 8h480c4.4 0 8-3.6 8-8v-56c0-4.4-3.6-8-8-8H408c-4.4 0-8 3.6-8 8v56zm504-486H120c-4.4 0-8 3.6-8 8v56c0 4.4 3.6 8 8 8h784c4.4 0 8-3.6 8-8v-56c0-4.4-3.6-8-8-8zm0 632H120c-4.4 0-8 3.6-8 8v56c0 4.4 3.6 8 8 8h784c4.4 0 8-3.6 8-8v-56c0-4.4-3.6-8-8-8zM115.4 518.9L271.7 642c5.8 4.6 14.4.5 14.4-6.9V388.9c0-7.4-8.5-11.5-14.4-6.9L115.4 505.1a8.74 8.74 0 0 0 0 13.8z"/>
</svg>
</symbol>
<symbol id="svg-menu" viewBox="0 0 24 24">
<title>Menu</title>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor"
stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather-menu">
<line x1="3" y1="12" x2="21" y2="12"></line>
<line x1="3" y1="6" x2="21" y2="6"></line>
<line x1="3" y1="18" x2="21" y2="18"></line>
</svg>
</symbol>
<symbol id="svg-arrow-right" viewBox="0 0 24 24">
<title>Expand</title>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor"
stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather-chevron-right">
<polyline points="9 18 15 12 9 6"></polyline>
</svg>
</symbol>
<symbol id="svg-sun" viewBox="0 0 24 24">
<title>Light mode</title>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor"
stroke-width="1" stroke-linecap="round" stroke-linejoin="round" class="feather-sun">
<circle cx="12" cy="12" r="5"></circle>
<line x1="12" y1="1" x2="12" y2="3"></line>
<line x1="12" y1="21" x2="12" y2="23"></line>
<line x1="4.22" y1="4.22" x2="5.64" y2="5.64"></line>
<line x1="18.36" y1="18.36" x2="19.78" y2="19.78"></line>
<line x1="1" y1="12" x2="3" y2="12"></line>
<line x1="21" y1="12" x2="23" y2="12"></line>
<line x1="4.22" y1="19.78" x2="5.64" y2="18.36"></line>
<line x1="18.36" y1="5.64" x2="19.78" y2="4.22"></line>
</svg>
</symbol>
<symbol id="svg-moon" viewBox="0 0 24 24">
<title>Dark mode</title>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor"
stroke-width="1" stroke-linecap="round" stroke-linejoin="round" class="icon-tabler-moon">
<path stroke="none" d="M0 0h24v24H0z" fill="none" />
<path d="M12 3c.132 0 .263 0 .393 0a7.5 7.5 0 0 0 7.92 12.446a9 9 0 1 1 -8.313 -12.454z" />
</svg>
</symbol>
<symbol id="svg-sun-with-moon" viewBox="0 0 24 24">
<title>Auto light/dark, in light mode</title>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor"
stroke-width="1" stroke-linecap="round" stroke-linejoin="round"
class="icon-custom-derived-from-feather-sun-and-tabler-moon">
<path style="opacity: 50%" d="M 5.411 14.504 C 5.471 14.504 5.532 14.504 5.591 14.504 C 3.639 16.319 4.383 19.569 6.931 20.352 C 7.693 20.586 8.512 20.551 9.25 20.252 C 8.023 23.207 4.056 23.725 2.11 21.184 C 0.166 18.642 1.702 14.949 4.874 14.536 C 5.051 14.512 5.231 14.5 5.411 14.5 L 5.411 14.504 Z"/>
<line x1="14.5" y1="3.25" x2="14.5" y2="1.25"/>
<line x1="14.5" y1="15.85" x2="14.5" y2="17.85"/>
<line x1="10.044" y1="5.094" x2="8.63" y2="3.68"/>
<line x1="19" y1="14.05" x2="20.414" y2="15.464"/>
<line x1="8.2" y1="9.55" x2="6.2" y2="9.55"/>
<line x1="20.8" y1="9.55" x2="22.8" y2="9.55"/>
<line x1="10.044" y1="14.006" x2="8.63" y2="15.42"/>
<line x1="19" y1="5.05" x2="20.414" y2="3.636"/>
<circle cx="14.5" cy="9.55" r="3.6"/>
</svg>
</symbol>
<symbol id="svg-moon-with-sun" viewBox="0 0 24 24">
<title>Auto light/dark, in dark mode</title>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor"
stroke-width="1" stroke-linecap="round" stroke-linejoin="round"
class="icon-custom-derived-from-feather-sun-and-tabler-moon">
<path d="M 8.282 7.007 C 8.385 7.007 8.494 7.007 8.595 7.007 C 5.18 10.184 6.481 15.869 10.942 17.24 C 12.275 17.648 13.706 17.589 15 17.066 C 12.851 22.236 5.91 23.143 2.505 18.696 C -0.897 14.249 1.791 7.786 7.342 7.063 C 7.652 7.021 7.965 7 8.282 7 L 8.282 7.007 Z"/>
<line style="opacity: 50%" x1="18" y1="3.705" x2="18" y2="2.5"/>
<line style="opacity: 50%" x1="18" y1="11.295" x2="18" y2="12.5"/>
<line style="opacity: 50%" x1="15.316" y1="4.816" x2="14.464" y2="3.964"/>
<line style="opacity: 50%" x1="20.711" y1="10.212" x2="21.563" y2="11.063"/>
<line style="opacity: 50%" x1="14.205" y1="7.5" x2="13.001" y2="7.5"/>
<line style="opacity: 50%" x1="21.795" y1="7.5" x2="23" y2="7.5"/>
<line style="opacity: 50%" x1="15.316" y1="10.184" x2="14.464" y2="11.036"/>
<line style="opacity: 50%" x1="20.711" y1="4.789" x2="21.563" y2="3.937"/>
<circle style="opacity: 50%" cx="18" cy="7.5" r="2.169"/>
</svg>
</symbol>
<symbol id="svg-pencil" viewBox="0 0 24 24">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor"
stroke-width="1" stroke-linecap="round" stroke-linejoin="round" class="icon-tabler-pencil-code">
<path d="M4 20h4l10.5 -10.5a2.828 2.828 0 1 0 -4 -4l-10.5 10.5v4" />
<path d="M13.5 6.5l4 4" />
<path d="M20 21l2 -2l-2 -2" />
<path d="M17 17l-2 2l2 2" />
</svg>
</symbol>
<symbol id="svg-eye" viewBox="0 0 24 24">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor"
stroke-width="1" stroke-linecap="round" stroke-linejoin="round" class="icon-tabler-eye-code">
<path stroke="none" d="M0 0h24v24H0z" fill="none" />
<path d="M10 12a2 2 0 1 0 4 0a2 2 0 0 0 -4 0" />
<path
d="M11.11 17.958c-3.209 -.307 -5.91 -2.293 -8.11 -5.958c2.4 -4 5.4 -6 9 -6c3.6 0 6.6 2 9 6c-.21 .352 -.427 .688 -.647 1.008" />
<path d="M20 21l2 -2l-2 -2" />
<path d="M17 17l-2 2l2 2" />
</svg>
</symbol>
</svg>
<input type="checkbox" class="sidebar-toggle" name="__navigation" id="__navigation" aria-label="Toggle site navigation sidebar">
<input type="checkbox" class="sidebar-toggle" name="__toc" id="__toc" aria-label="Toggle table of contents sidebar">
<label class="overlay sidebar-overlay" for="__navigation"></label>
<label class="overlay toc-overlay" for="__toc"></label>
<a class="skip-to-content muted-link" href="#furo-main-content">Skip to content</a>
<div class="page">
<header class="mobile-header">
<div class="header-left">
<label class="nav-overlay-icon" for="__navigation">
<span class="icon"><svg><use href="#svg-menu"></use></svg></span>
</label>
</div>
<div class="header-center">
<a href="../../"><div class="brand">LXD documentation</div></a>
</div>
<div class="header-right">
<div class="theme-toggle-container theme-toggle-header">
<button class="theme-toggle" aria-label="Toggle Light / Dark / Auto color theme">
<svg class="theme-icon-when-auto-light"><use href="#svg-sun-with-moon"></use></svg>
<svg class="theme-icon-when-auto-dark"><use href="#svg-moon-with-sun"></use></svg>
<svg class="theme-icon-when-dark"><use href="#svg-moon"></use></svg>
<svg class="theme-icon-when-light"><use href="#svg-sun"></use></svg>
</button>
</div>
<label class="toc-overlay-icon toc-header-icon" for="__toc">
<span class="icon"><svg><use href="#svg-toc"></use></svg></span>
</label>
</div>
</header>
<aside class="sidebar-drawer">
<div class="sidebar-container">
<div class="sidebar-sticky"><a class="sidebar-brand" href="../../">
<span class="sidebar-brand-text">LXD documentation</span>
</a><form class="sidebar-search-container" method="get" action="../../search/" role="search">
<input class="sidebar-search" placeholder="Search" name="q" aria-label="Search">
<input type="submit" value="Go">
<input type="hidden" name="check_keywords" value="yes">
<input type="hidden" name="area" value="default">
</form>
<div id="searchbox"></div><div class="sidebar-scroll"><div class="sidebar-tree">
<ul class="current">
<li class="toctree-l1"><a class="reference internal" href="../../">LXD</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../tutorial/first_steps/">Tutorial</a></li>
<li class="toctree-l1 has-children"><a class="reference internal" href="../../howto/">How-to guides</a><input aria-label="Toggle navigation of How-to guides" class="toctree-checkbox" id="toctree-checkbox-1" name="toctree-checkbox-1" role="switch" type="checkbox"/><label for="toctree-checkbox-1"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../getting_started/">Getting started</a><input aria-label="Toggle navigation of Getting started" class="toctree-checkbox" id="toctree-checkbox-2" name="toctree-checkbox-2" role="switch" type="checkbox"/><label for="toctree-checkbox-2"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../installing/">Install LXD</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/initialize/">Initialize LXD</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/access_ui/">Access the UI</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/access_documentation/">Access documentation locally</a></li>
</ul>
</li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../operation/">LXD server and client</a><input aria-label="Toggle navigation of LXD server and client" class="toctree-checkbox" id="toctree-checkbox-3" name="toctree-checkbox-3" role="switch" type="checkbox"/><label for="toctree-checkbox-3"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/server_expose/">Expose LXD to the network</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/server_configure/">Configure the LXD server</a></li>
<li class="toctree-l3 has-children"><a class="reference internal" href="../../howto/oidc/">Configure single sign-on with OIDC</a><input aria-label="Toggle navigation of Configure single sign-on with OIDC" class="toctree-checkbox" id="toctree-checkbox-4" name="toctree-checkbox-4" role="switch" type="checkbox"/><label for="toctree-checkbox-4"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l4"><a class="reference internal" href="../../howto/oidc_auth0/">How to configure Auth0</a></li>
<li class="toctree-l4"><a class="reference internal" href="../../howto/oidc_ory/">How to configure Ory Hydra</a></li>
<li class="toctree-l4"><a class="reference internal" href="../../howto/oidc_keycloak/">How to configure Keycloak</a></li>
<li class="toctree-l4"><a class="reference internal" href="../../howto/oidc_entra_id/">How to configure Entra ID</a></li>
</ul>
</li>
<li class="toctree-l3"><a class="reference internal" href="../../remotes/">Add remote servers</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/lxc_alias/">Add command aliases</a></li>
</ul>
</li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../instances/">Instances</a><input aria-label="Toggle navigation of Instances" class="toctree-checkbox" id="toctree-checkbox-5" name="toctree-checkbox-5" role="switch" type="checkbox"/><label for="toctree-checkbox-5"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_create/">Create instances</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_configure/">Configure instances</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_manage/">Manage instances</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../profiles/">Use profiles</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_troubleshoot/">Troubleshoot errors</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_ubuntu_pro_attach/">Auto attach Ubuntu Pro</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_access_files/">Access files</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_console/">Access the console</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../instance-exec/">Run commands</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../cloud-init/">Use cloud-init</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_routed_nic_vm/">Add a routed NIC to a VM</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_backup/">Back up instances</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_migrate/">Migrate instances</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/import_machines_to_instances/">Import existing machines</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/container_gpu_passthrough_with_docker/">Pass NVIDIA GPUs</a></li>
</ul>
</li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../images/">Images</a><input aria-label="Toggle navigation of Images" class="toctree-checkbox" id="toctree-checkbox-6" name="toctree-checkbox-6" role="switch" type="checkbox"/><label for="toctree-checkbox-6"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/images_remote/">Use remote images</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/images_manage/">Manage images</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/images_profiles/">Associate profiles</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/images_copy/">Copy and import images</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/images_create/">Create images</a></li>
</ul>
</li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../projects/">Projects</a><input aria-label="Toggle navigation of Projects" class="toctree-checkbox" id="toctree-checkbox-7" name="toctree-checkbox-7" role="switch" type="checkbox"/><label for="toctree-checkbox-7"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/projects_create/">Create and configure</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/projects_work/">Work with projects</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/projects_confine/">Confine users to projects</a></li>
</ul>
</li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../storage/">Storage</a><input aria-label="Toggle navigation of Storage" class="toctree-checkbox" id="toctree-checkbox-8" name="toctree-checkbox-8" role="switch" type="checkbox"/><label for="toctree-checkbox-8"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/storage_pools/">Manage pools</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/storage_volumes/">Manage volumes</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/storage_buckets/">Manage buckets</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/storage_create_instance/">Create an instance in a pool</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/storage_backup_volume/">Back up a volume</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/storage_move_volume/">Move or copy a volume</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/storage_csi/">Use the LXD CSI driver with Kubernetes</a></li>
</ul>
</li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../networks/">Networking</a><input aria-label="Toggle navigation of Networking" class="toctree-checkbox" id="toctree-checkbox-9" name="toctree-checkbox-9" role="switch" type="checkbox"/><label for="toctree-checkbox-9"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_create/">Create a network</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_configure/">Configure a network</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_bgp/">Configure as BGP server</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_acls/">Configure network ACLs</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_forwards/">Configure forwards</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_zones/">Configure network zones</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_bridge_firewalld/">Configure your firewall</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_bridge_resolved/">Integrate with resolved</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_ovn_setup/">Set up OVN</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_load_balancers/">Configure load balancers</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_ovn_peers/">Configure peer routing</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_ipam/">Display IPAM information</a></li>
</ul>
</li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../clustering/">Clustering</a><input aria-label="Toggle navigation of Clustering" class="toctree-checkbox" id="toctree-checkbox-10" name="toctree-checkbox-10" role="switch" type="checkbox"/><label for="toctree-checkbox-10"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/cluster_form/">Form a cluster</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/cluster_manage/">Manage a cluster</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/cluster_config_networks/">Configure networks</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/cluster_config_storage/">Configure storage</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/cluster_manage_instance/">Manage instances</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/cluster_groups/">Set up cluster groups</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/cluster_placement_groups/">Use placement groups</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/cluster_recover/">Recover a cluster</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/cluster_vip/">Set up a highly available virtual IP</a></li>
</ul>
</li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../production-setup/">Production setup</a><input aria-label="Toggle navigation of Production setup" class="toctree-checkbox" id="toctree-checkbox-11" name="toctree-checkbox-11" role="switch" type="checkbox"/><label for="toctree-checkbox-11"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/benchmark_performance/">Benchmark performance</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_increase_bandwidth/">Increase bandwidth</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../metrics/">Monitor metrics</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/logs_loki/">Send logs to Loki</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/grafana/">Set up Grafana</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../backup/">Back up a server</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/disaster_recovery/">Recover instances</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/disaster_recovery_replication/">Disaster recovery with storage replication</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../../howto/snap/">Manage the snap</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../howto/security_harden/">Harden security</a></li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../howto/troubleshoot/">Troubleshooting</a><input aria-label="Toggle navigation of Troubleshooting" class="toctree-checkbox" id="toctree-checkbox-12" name="toctree-checkbox-12" role="switch" type="checkbox"/><label for="toctree-checkbox-12"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/network_bridge_firewalld/">Configure your firewall</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/instances_troubleshoot/">Troubleshoot instances</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/dqlite_troubleshoot/">Troubleshoot Dqlite</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../debugging/">Debug LXD</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../faq/">Frequently asked</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../../support/">Get support</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../contributing/">Contribute to LXD</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../howto/auth_bearer/">How to authenticate to the LXD API using bearer tokens</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../howto/devlxd_authenticate/">How to authenticate to the DevLXD API</a></li>
</ul>
</li>
<li class="toctree-l1 has-children"><a class="reference internal" href="../../explanation/">Explanation</a><input aria-label="Toggle navigation of Explanation" class="toctree-checkbox" id="toctree-checkbox-13" name="toctree-checkbox-13" role="switch" type="checkbox"/><label for="toctree-checkbox-13"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/lxd_lxc/"><code class="docutils literal notranslate"><span class="pre">lxd</span></code> and <code class="docutils literal notranslate"><span class="pre">lxc</span></code></a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/instances/">Containers and VMs</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../image-handling/">Local and remote images</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/storage/">Storage pools, volumes, and buckets</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/networks/">Networking setups</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../database/">The LXD Dqlite database</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/lxc_show_info/"><code class="docutils literal notranslate"><span class="pre">lxc</span></code> <code class="docutils literal notranslate"><span class="pre">show</span></code> and <code class="docutils literal notranslate"><span class="pre">info</span></code></a></li>
<li class="toctree-l2"><a class="reference internal" href="../../authentication/">Remote API authentication</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/authorization/">Remote API authorization</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/projects/">Instances grouping with projects</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/clusters/">Clusters</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/performance_tuning/">Performance tuning</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/security/">Security</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/bpf/">Privilege delegation using BPF Token</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../explanation/csi/">The LXD CSI driver</a></li>
</ul>
</li>
<li class="toctree-l1 current has-children"><a class="reference internal" href="../">Reference</a><input aria-label="Toggle navigation of Reference" checked="" class="toctree-checkbox" id="toctree-checkbox-14" name="toctree-checkbox-14" role="switch" type="checkbox"/><label for="toctree-checkbox-14"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul class="current">
<li class="toctree-l2"><a class="reference internal" href="../../requirements/">Requirements</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../architectures/">Architectures</a></li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../release-notes/">Release notes</a><input aria-label="Toggle navigation of Release notes" class="toctree-checkbox" id="toctree-checkbox-15" name="toctree-checkbox-15" role="switch" type="checkbox"/><label for="toctree-checkbox-15"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../release-notes/release-notes-6.7/">LXD 6.7</a></li>
<li class="toctree-l3"><a class="reference internal" href="../release-notes/release-notes-6.6/">LXD 6.6</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../releases-snap/">Releases and snap</a></li>
<li class="toctree-l2"><a class="reference internal" href="../remote_image_servers/">Remote image servers</a></li>
<li class="toctree-l2"><a class="reference internal" href="../image_format/">Image format</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../guest-os-compatibility/">Guest OS compatibility</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../container-environment/">Container environment</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../config-options/">Configuration option index</a></li>
<li class="toctree-l2"><a class="reference internal" href="../../server/">Server configuration</a></li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../explanation/instance_config/">Instance configuration</a><input aria-label="Toggle navigation of Instance configuration" class="toctree-checkbox" id="toctree-checkbox-16" name="toctree-checkbox-16" role="switch" type="checkbox"/><label for="toctree-checkbox-16"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../instance_properties/">Instance properties</a></li>
<li class="toctree-l3"><a class="reference internal" href="../instance_options/">Instance options</a></li>
<li class="toctree-l3 has-children"><a class="reference internal" href="../devices/">Devices</a><input aria-label="Toggle navigation of Devices" class="toctree-checkbox" id="toctree-checkbox-17" name="toctree-checkbox-17" role="switch" type="checkbox"/><label for="toctree-checkbox-17"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l4"><a class="reference internal" href="../standard_devices/">Standard devices</a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_none/">Type: <code class="docutils literal notranslate"><span class="pre">none</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_nic/">Type: <code class="docutils literal notranslate"><span class="pre">nic</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_disk/">Type: <code class="docutils literal notranslate"><span class="pre">disk</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_unix_char/">Type: <code class="docutils literal notranslate"><span class="pre">unix-char</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_unix_block/">Type: <code class="docutils literal notranslate"><span class="pre">unix-block</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_usb/">Type: <code class="docutils literal notranslate"><span class="pre">usb</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_gpu/">Type: <code class="docutils literal notranslate"><span class="pre">gpu</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_infiniband/">Type: <code class="docutils literal notranslate"><span class="pre">infiniband</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_proxy/">Type: <code class="docutils literal notranslate"><span class="pre">proxy</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_unix_hotplug/">Type: <code class="docutils literal notranslate"><span class="pre">unix-hotplug</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_tpm/">Type: <code class="docutils literal notranslate"><span class="pre">tpm</span></code></a></li>
<li class="toctree-l4"><a class="reference internal" href="../devices_pci/">Type: <code class="docutils literal notranslate"><span class="pre">pci</span></code></a></li>
</ul>
</li>
<li class="toctree-l3"><a class="reference internal" href="../instance_units/">Units for storage and network limits</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../preseed_yaml_fields/">Preseed YAML file fields</a></li>
<li class="toctree-l2"><a class="reference internal" href="../projects/">Project configuration</a></li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../storage_drivers/">Storage drivers</a><input aria-label="Toggle navigation of Storage drivers" class="toctree-checkbox" id="toctree-checkbox-18" name="toctree-checkbox-18" role="switch" type="checkbox"/><label for="toctree-checkbox-18"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../storage_dir/">Directory - <code class="docutils literal notranslate"><span class="pre">dir</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="../storage_btrfs/">Btrfs - <code class="docutils literal notranslate"><span class="pre">btrfs</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="../storage_lvm/">LVM - <code class="docutils literal notranslate"><span class="pre">lvm</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="../storage_zfs/">ZFS - <code class="docutils literal notranslate"><span class="pre">zfs</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="../storage_ceph/">Ceph RBD - <code class="docutils literal notranslate"><span class="pre">ceph</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="../storage_powerflex/">Dell PowerFlex - <code class="docutils literal notranslate"><span class="pre">powerflex</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="../storage_pure/">Pure Storage - <code class="docutils literal notranslate"><span class="pre">pure</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="../storage_alletra/">HPE Alletra - <code class="docutils literal notranslate"><span class="pre">alletra</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="../storage_cephfs/">CephFS - <code class="docutils literal notranslate"><span class="pre">cephfs</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="../storage_cephobject/">Ceph Object - <code class="docutils literal notranslate"><span class="pre">cephobject</span></code></a></li>
</ul>
</li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../networks/">Networks</a><input aria-label="Toggle navigation of Networks" class="toctree-checkbox" id="toctree-checkbox-19" name="toctree-checkbox-19" role="switch" type="checkbox"/><label for="toctree-checkbox-19"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../network_bridge/">Bridge network</a></li>
<li class="toctree-l3"><a class="reference internal" href="../network_ovn/">OVN network</a></li>
<li class="toctree-l3"><a class="reference internal" href="../network_macvlan/">Macvlan network</a></li>
<li class="toctree-l3"><a class="reference internal" href="../network_physical/">Physical network</a></li>
<li class="toctree-l3"><a class="reference internal" href="../network_sriov/">SR-IOV network</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../cluster_member_config/">Cluster configuration</a></li>
<li class="toctree-l2"><a class="reference internal" href="../placement_groups/">Placement group configuration</a></li>
<li class="toctree-l2"><a class="reference internal" href="../server_settings/">Production server settings</a></li>
<li class="toctree-l2"><a class="reference internal" href="../provided_metrics/">Provided metrics</a></li>
<li class="toctree-l2"><a class="reference internal" href="../permissions/">Permissions</a></li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../../restapi_landing/">REST API</a><input aria-label="Toggle navigation of REST API" class="toctree-checkbox" id="toctree-checkbox-20" name="toctree-checkbox-20" role="switch" type="checkbox"/><label for="toctree-checkbox-20"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../../rest-api/">Main API documentation</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../api/">Main API specification</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../api-extensions/">Main API extensions</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../events/">Events API documentation</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../dev-lxd/">Instance API</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../driver_csi/">LXD CSI driver reference</a></li>
<li class="toctree-l2 has-children"><a class="reference internal" href="../manpages/">Man pages</a><input aria-label="Toggle navigation of Man pages" class="toctree-checkbox" id="toctree-checkbox-21" name="toctree-checkbox-21" role="switch" type="checkbox"/><label for="toctree-checkbox-21"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul>
<li class="toctree-l3"><a class="reference internal" href="../manpages/lxc/"><code class="docutils literal notranslate"><span class="pre">lxc</span></code></a></li>
</ul>
</li>
<li class="toctree-l2 current has-children"><a class="reference internal" href="../../internals/">Internals</a><input aria-label="Toggle navigation of Internals" checked="" class="toctree-checkbox" id="toctree-checkbox-22" name="toctree-checkbox-22" role="switch" type="checkbox"/><label for="toctree-checkbox-22"><span class="icon"><svg><use href="#svg-arrow-right"></use></svg></span></label><ul class="current">
<li class="toctree-l3"><a class="reference internal" href="../../environment/">Environment variables</a></li>
<li class="toctree-l3"><a class="reference internal" href="../uefi_variables/">UEFI variables for VMs</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../daemon-behavior/">Daemon behavior</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../syscall-interception/">System call interception</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../userns-idmap/">User namespace setup</a></li>
<li class="toctree-l3"><a class="reference internal" href="../ovn-internals/">OVN implementation</a></li>
<li class="toctree-l3 current current-page"><a class="current reference internal" href="#">VM live migration implementation</a></li>
<li class="toctree-l3"><a class="reference internal" href="../dqlite-internals/">Dqlite</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference external" href="https://github.com/canonical/lxd">Project repository</a></li>
<li class="toctree-l2"><a class="reference external" href="https://images.lxd.canonical.com">Image server</a></li>
</ul>
</li>
</ul>
</div>
</div>
</div>
</div>
</aside>
<div class="main">
<div class="content">
<div class="article-container">
<a href="#" class="back-to-top muted-link">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
<path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8v12z"></path>
</svg>
<span>Back to top</span>
</a>
<div class="content-icon-container">
<div class="edit-this-page">
<a class="muted-link" href="https://github.com/canonical/lxd/edit/main/doc/reference/vm_live_migration_internals.md" title="Contribute to this page">
<svg><use href="#svg-pencil"></use></svg>
<span class="visually-hidden">Contribute to this page</span>
</a>
</div><div class="theme-toggle-container theme-toggle-content">
<button class="theme-toggle" aria-label="Toggle Light / Dark / Auto color theme">
<svg class="theme-icon-when-auto-light"><use href="#svg-sun-with-moon"></use></svg>
<svg class="theme-icon-when-auto-dark"><use href="#svg-moon-with-sun"></use></svg>
<svg class="theme-icon-when-dark"><use href="#svg-moon"></use></svg>
<svg class="theme-icon-when-light"><use href="#svg-sun"></use></svg>
</button>
</div>
<label class="toc-overlay-icon toc-content-icon" for="__toc">
<span class="icon"><svg><use href="#svg-toc"></use></svg></span>
</label>
</div>
<article role="main" id="furo-main-content">
<section id="vm-live-migration-implementation">
<span id="vm-live-migration-internals"></span><h1>VM live migration implementation<a class="headerlink" href="#vm-live-migration-implementation" title="Link to this heading">¶</a></h1>
<p><a class="reference internal" href="../../howto/instances_migrate/#live-migration"><span class="std std-ref">Live migration</span></a> in LXD is achieved by streaming instance state from a source <abbr title="Quick Emulator">QEMU</abbr> to a target QEMU. VM live migration is supported for all storage pool types.</p>
<p>API extension: <code class="docutils literal notranslate"><span class="pre">migration_vm_live</span></code></p>
<section id="conceptual-process">
<h2>Conceptual process<a class="headerlink" href="#conceptual-process" title="Link to this heading">¶</a></h2>
<p>The live migration workflow varies depending on the type of storage pool used. The two key scenarios are non-shared storage and shared storage within a cluster (e.g., Ceph). If live state transfer is not supported by a target, a stateful stop is performed prior to migration.</p>
<section id="live-migration-for-non-shared-storage">
<h3>Live migration for non-shared storage<a class="headerlink" href="#live-migration-for-non-shared-storage" title="Link to this heading">¶</a></h3>
<p>This process leverages the QEMU built-in Network Block Device (NBD) client-server mechanism to transfer the virtual machine’s disk and memory state. Below is an overview of the steps:</p>
<ol class="arabic simple">
<li><p>Set up connection.</p></li>
<li><p>Determine migration type (shared or non-shared storage).</p></li>
<li><p>Set migration capabilities.</p></li>
<li><p>Non-shared storage preparation.</p>
<ol class="arabic simple">
<li><p>Create and configure snapshot file for root disk writes during migration.</p></li>
<li><p>Add the snapshot as a block device to the source VM.</p></li>
<li><p>Redirect disk writes to the snapshot.</p></li>
</ol>
</li>
<li><p>Storage transfer.</p>
<ol class="arabic simple">
<li><p>For shared storage, we just perform checks at this point.</p></li>
<li><p>For non-shared storage, set up an NBD listener and connect it to the target to transfer the disk.</p></li>
</ol>
</li>
<li><p>Snapshot sync for non-shared storage to ensure consistency between source and target.</p></li>
<li><p>Transfer VM state to target.</p></li>
</ol>
<figure class="align-default" id="id1">
<img alt="../../_images/vm_live_migration_flowchart.svg" src="../../_images/vm_live_migration_flowchart.svg" />
<figcaption>
<p><span class="caption-text">Non-Shared Storage Migration</span><a class="headerlink" href="#id1" title="Link to this image">¶</a></p>
</figcaption>
</figure>
<p>The state transitions during the process are shown below:</p>
<figure class="align-default" id="id2">
<img alt="../../_images/vm_live_migration_state_diagram.svg" src="../../_images/vm_live_migration_state_diagram.svg" />
<figcaption>
<p><span class="caption-text">Non-Shared Storage Migration State Transitions</span><a class="headerlink" href="#id2" title="Link to this image">¶</a></p>
</figcaption>
</figure>
</section>
<section id="intra-cluster-member-live-migration-ceph-shared-storage-pool">
<h3>Intra-cluster member live migration (Ceph shared storage pool)<a class="headerlink" href="#intra-cluster-member-live-migration-ceph-shared-storage-pool" title="Link to this heading">¶</a></h3>
<p>For shared storage pools such as Ceph, disk data transfer is unnecessary. Instead, the process focuses on transferring the VM state through a dedicated migration socket:</p>
<ol class="arabic simple">
<li><p>Validate cluster state and storage pool readiness.</p></li>
<li><p>Notify the shared disks that they will be accessed from another system.</p></li>
<li><p>Pause the guest OS on the source VM and transfer the live state data over the migration socket.</p></li>
<li><p>Stop and delete source VM.</p></li>
<li><p>Start the target VM using the transferred state.</p></li>
</ol>
</section>
</section>
<section id="migration-api">
<h2>Migration API<a class="headerlink" href="#migration-api" title="Link to this heading">¶</a></h2>
<p>Sending a <code class="docutils literal notranslate"><span class="pre">POST</span></code> request to <code class="docutils literal notranslate"><span class="pre">/1.0/instances/{name}</span></code> renames, moves an instance between pools, or migrates an instance to another server. In the push case, the returned operation metadata for migration is a background operation with progress data. For the pull case, it is a WebSocket operation with a number of secrets to be passed to the target server.</p>
</section>
<section id="live-migration-call-stack">
<h2>Live migration call stack<a class="headerlink" href="#live-migration-call-stack" title="Link to this heading">¶</a></h2>
<p>Below is a general overview of the key functions of the live migration call stack:</p>
<section id="lxd-lxd-instance-post-go">
<h3><a class="reference external" href="https://github.com/canonical/lxd/blob/main/lxd/instance_post.go"><code class="docutils literal notranslate"><span class="pre">lxd/lxd/instance_post.go</span></code></a><a class="headerlink" href="#lxd-lxd-instance-post-go" title="Link to this heading">¶</a></h3>
<p><a class="reference external" href="https://github.com/canonical/lxd/blob/main/lxd/instance_post.go#L74"><code class="docutils literal notranslate"><span class="pre">instancePost</span></code></a></p>
<p>This function handles post requests to the <code class="docutils literal notranslate"><span class="pre">/1.0/instances</span></code> endpoint.</p>
</section>
<section id="lxd-lxd-migrate-instance-go">
<h3><a class="reference external" href="https://github.com/canonical/lxd/blob/main/lxd/migrate_instance.go"><code class="docutils literal notranslate"><span class="pre">lxd/lxd/migrate_instance.go</span></code></a><a class="headerlink" href="#lxd-lxd-migrate-instance-go" title="Link to this heading">¶</a></h3>
<p><a class="reference external" href="https://github.com/canonical/lxd/blob/main/lxd/migrate_instance.go#L87"><code class="docutils literal notranslate"><span class="pre">Do</span></code></a></p>
<p>This function performs the migration operation on the source VM for the given state and operation. It sets up the necessary WebSocket connections for control, state, and filesystem, and then initiates the migration process.</p>
</section>
<section id="lxd-lxd-instance-drivers-driver-qemu-go">
<h3><a class="reference external" href="https://github.com/canonical/lxd/blob/main/lxd/instance/drivers/driver_qemu.go"><code class="docutils literal notranslate"><span class="pre">lxd/lxd/instance/drivers/driver_qemu.go</span></code></a><a class="headerlink" href="#lxd-lxd-instance-drivers-driver-qemu-go" title="Link to this heading">¶</a></h3>
<p><a class="reference external" href="https://github.com/canonical/lxd/blob/main/lxd/instance/drivers/driver_qemu.go#L6436"><code class="docutils literal notranslate"><span class="pre">MigrateSend</span></code></a></p>
<p>This function controls the sending of a migration, checking for stateful support, waiting for connections, performing checks, and sending a migration offer. When performing an intra-cluster same-name migration, steps are taken to prevent corruption of volatile device configuration keys during the start and stop of the instance on both source and target.</p>
<p><a class="reference external" href="https://github.com/canonical/lxd/blob/main/lxd/instance/drivers/driver_qemu.go#L6666"><code class="docutils literal notranslate"><span class="pre">migrateSendLive</span></code></a></p>
<p>This function performs the live migration send process:</p>
<ol class="arabic simple">
<li><p>Connect to the QEMU monitor: The function begins by establishing a connection to the QEMU monitor using <code class="docutils literal notranslate"><span class="pre">qmp.Connect</span></code>.</p></li>
<li><p>Define disk names: The function defines names for the root disk (<code class="docutils literal notranslate"><span class="pre">lxd_root</span></code>), the NBD target disk (<code class="docutils literal notranslate"><span class="pre">lxd_root_nbd</span></code>), and the snapshot disk (<code class="docutils literal notranslate"><span class="pre">lxd_root_snapshot</span></code>). These will be used later to manage the root disk and its snapshot during migration.</p></li>
<li><p>Check for shared storage: If the migration involves shared storage, the migration process can bypass the need for synchronizing the root disk. The function checks for this condition by verifying if <code class="docutils literal notranslate"><span class="pre">clusterMoveSourceName</span></code> is non-empty and the pool is remote.</p></li>
<li><p>Non-shared storage snapshot setup: If shared storage is not used, the function proceeds to set up a temporary snapshot of the root disk.</p>
<ol class="arabic simple">
<li><p>Migration capabilities such as <code class="docutils literal notranslate"><span class="pre">auto-converge</span></code>, <code class="docutils literal notranslate"><span class="pre">pause-before-switchover</span></code>, and <code class="docutils literal notranslate"><span class="pre">zero-blocks</span></code> are set to optimize the migration process.</p></li>
<li><p>The function creates a QCOW2 snapshot file of the root disk, which will store changes to the disk during migration.</p></li>
<li><p>The snapshot file is opened for reading and writing, and the file descriptor is passed to QEMU.</p></li>
<li><p>The snapshot is added as a block device to QEMU, ensuring that it is not visible to the guest OS.</p></li>
<li><p>A snapshot of the root disk is taken using <code class="docutils literal notranslate"><span class="pre">monitor.BlockDevSnapshot</span></code>. This ensures that changes to the root disk are isolated during migration.</p></li>
<li><p>Revert function: The revert function is used to clean up in case of failure. It ensures that the guest is resumed, and any changes made during snapshot creation are merged back into the root disk if migration fails</p></li>
</ol>
</li>
<li><p>Shared storage setup: If shared storage is used, only the <code class="docutils literal notranslate"><span class="pre">auto-converge</span></code> migration capability is set, and no snapshot creation is necessary.</p></li>
<li><p>Perform storage transfer: The storage pool is migrated while the VM is still running. The <code class="docutils literal notranslate"><span class="pre">volSourceArgs.AllowInconsistent</span></code> flag is set to true to allow migration while the disk is in use. The migration checks are done by calling <code class="docutils literal notranslate"><span class="pre">pool.MigrateInstance</span></code>.</p></li>
<li><p>Notify shared disk pools: For each disk in the VM, the migration process checks if the disk belongs to a shared pool. If so, the disk is prepared for migration by calling <code class="docutils literal notranslate"><span class="pre">MigrateVolume</span></code> on the source disk.</p></li>
<li><p>Set up NBD listener and connection: If shared storage is not used, the function sets up a Unix socket listener for NBD connections. This listener handles the actual data transfer of the root disk from the source VM to the migration target.</p></li>
<li><p>Begin block device mirroring: After setting up the NBD connection, the function starts transferring the migration snapshot to the target disk by using <code class="docutils literal notranslate"><span class="pre">monitor.BlockDevMirror</span></code>.</p></li>
<li><p>Send stateful migration checkpoint: The function creates a pipe to transfer the state of the VM during the migration process. It writes the VMs state to the <code class="docutils literal notranslate"><span class="pre">stateConn</span></code> via the pipe, using <code class="docutils literal notranslate"><span class="pre">d.saveStateHandle</span></code> to handle the state transfer. Note that the source VMs guest OS is paused while the state is transferred. This ensures that the VMs state is consistent when the migration completes.</p></li>
<li><p>Finalize snapshot transfer: If non-shared storage is used, the function waits for the state transfer to reach the <code class="docutils literal notranslate"><span class="pre">pre-switchover</span></code> stage, ensuring that the guest remains paused during this process. Next, the function cancels the block job associated with the root snapshot to finalize the transfer and ensure that no changes are lost.</p></li>
<li><p>Completion: Once all transfers are complete, the function proceeds to finalize the migration process by resuming the target VM and ensuring that source VM resources are cleaned up. The source VM is stopped, and its storage is discarded.</p></li>
</ol>
</section>
</section>
</section>
</article>
</div>
<footer>
<div class="related-pages">
<a class="next-page" href="../dqlite-internals/">
<div class="page-info">
<div class="context">
<span>Next</span>
</div>
<div class="title">Dqlite internals</div>
</div>
<svg class="furo-related-icon"><use href="#svg-arrow-right"></use></svg>
</a>
<a class="prev-page" href="../ovn-internals/">
<svg class="furo-related-icon"><use href="#svg-arrow-right"></use></svg>
<div class="page-info">
<div class="context">
<span>Previous</span>
</div>
<div class="title">OVN implementation</div>
</div>
</a>
</div>
<div class="bottom-of-page">
<div class="left-details">
<div class="copyright">
© 2014-2026 AGPL-3.0, LXD contributors
</div><div class="last-updated">
Last updated on Feb 13, 2026</div>
</div>
<div class="right-details">
<a href="" class="js-revoke-cookie-manager muted-link">Manage your tracker settings</a>
</div>
</footer>
</div>
<aside class="toc-drawer">
<div class="toc-sticky toc-scroll">
<div class="toc-title-container">
<span class="toc-title">
Contents
</span>
</div>
<div class="toc-tree-container">
<div class="toc-tree">
<ul>
<li><a class="reference internal" href="#">VM live migration implementation</a><ul>
<li><a class="reference internal" href="#conceptual-process">Conceptual process</a><ul>
<li><a class="reference internal" href="#live-migration-for-non-shared-storage">Live migration for non-shared storage</a></li>
<li><a class="reference internal" href="#intra-cluster-member-live-migration-ceph-shared-storage-pool">Intra-cluster member live migration (Ceph shared storage pool)</a></li>
</ul>
</li>
<li><a class="reference internal" href="#migration-api">Migration API</a></li>
<li><a class="reference internal" href="#live-migration-call-stack">Live migration call stack</a><ul>
<li><a class="reference internal" href="#lxd-lxd-instance-post-go"><code class="docutils literal notranslate"><span class="pre">lxd/lxd/instance_post.go</span></code></a></li>
<li><a class="reference internal" href="#lxd-lxd-migrate-instance-go"><code class="docutils literal notranslate"><span class="pre">lxd/lxd/migrate_instance.go</span></code></a></li>
<li><a class="reference internal" href="#lxd-lxd-instance-drivers-driver-qemu-go"><code class="docutils literal notranslate"><span class="pre">lxd/lxd/instance/drivers/driver_qemu.go</span></code></a></li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
</div>
<div class="relatedlinks-title-container">
<span class="relatedlinks-title">
Related links
</span>
</div>
<div class="relatedlinks-container">
<div class="relatedlinks">
<ul><li><a href="https://discourse.ubuntu.com/t/50734" target="_blank">Online VM live-migration (QEMU to QEMU)</a></li></ul>
</div>
</div>
</div>
</aside>
</div>
</div><script src="../../_static/jquery.js?v=5d32c60e"></script>
<script src="../../_static/_sphinx_javascript_frameworks_compat.js?v=2cd50e6c"></script>
<script src="../../_static/documentation_options.js?v=a5603611"></script>
<script src="../../_static/doctools.js?v=9a2dae69"></script>
<script src="../../_static/sphinx_highlight.js?v=dc90522c"></script>
<script src="../../_static/scripts/furo.js?v=46bd48cc"></script>
<script src="../../_static/clipboard.min.js?v=a7894cd8"></script>
<script src="../../_static/copybutton.js?v=b01cb6f2"></script>
<script src="../../_static/config-options.js"></script>
<script src="../../_static/design-tabs.js?v=f930bc37"></script>
<script src="../../_static/js/bundle.js?v=a4d88309"></script>
<script src="../../_static/header-nav.js?v=e117ad08"></script>
<script src="../../_static/github_issue_links.js?v=32bb732f"></script>
<script>
const github_url = "https://github.com/canonical/lxd";
</script>
</body>
</html>