https://blog.ohtly.com/tags/hotplug/ Recent content in Hotplug on OHTLY Blog Hugo zh-cn Sun, 05 Jul 2026 11:06:34 +0800 https://blog.ohtly.com/posts/2026-07-05-pve-memory-hotplug-balloon/ Sun, 05 Jul 2026 11:03:00 +0800 https://blog.ohtly.com/posts/2026-07-05-pve-memory-hotplug-balloon/ <h2 id="背景"> 背景 <a class="heading-link" href="#%e8%83%8c%e6%99%af"> <i class="fa-solid fa-link" aria-hidden="true" title="链接到标题"></i> <span class="sr-only">链接到标题</span> </a> </h2> <p>PVE 虚拟机调整内存有两种常见场景：</p> <ol> <li><strong>扩容</strong>：虚拟机需要更多内存，希望不停机直接添加</li> <li><strong>宿主机压力回收</strong>：宿主机内存不足时，临时压缩虚拟机内存</li> </ol> <p>传统方式需要关机修改再开机，导致服务中断。通过 Hotplug 和 Ballooning 可以解决这两个问题。</p> <h2 id="内存热添加hotplug"> 内存热添加（Hotplug） <a class="heading-link" href="#%e5%86%85%e5%ad%98%e7%83%ad%e6%b7%bb%e5%8a%a0hotplug"> <i class="fa-solid fa-link" aria-hidden="true" title="链接到标题"></i> <span class="sr-only">链接到标题</span> </a> </h2> <h3 id="原理"> 原理 <a class="heading-link" href="#%e5%8e%9f%e7%90%86"> <i class="fa-solid fa-link" aria-hidden="true" title="链接到标题"></i> <span class="sr-only">链接到标题</span> </a> </h3> <p>QEMU 在启动时可以预留内存槽位（slots）和最大内存上限（maxmem），运行中通过 <code>device_add</code> 命令插入 pc-dimm 设备来增加内存。</p> <h3 id="配置步骤"> 配置步骤 <a class="heading-link" href="#%e9%85%8d%e7%bd%ae%e6%ad%a5%e9%aa%a4"> <i class="fa-solid fa-link" aria-hidden="true" title="链接到标题"></i> <span class="sr-only">链接到标题</span> </a> </h3> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span><span style="color:#75715e"># 1. 启用 memory hotplug 和 numa</span> </span></span><span style="display:flex;"><span>qm set &lt;vmid&gt; --hotplug <span style="color:#e6db74">&#34;memory&#34;</span> </span></span><span style="display:flex;"><span>qm set &lt;vmid&gt; --numa <span style="color:#ae81ff">1</span> </span></span><span style="display:flex;"><span> </span></span><span style="display:flex;"><span><span style="color:#75715e"># 2. 首次需要 shutdown + start（让 QEMU 带上 slots/maxmem 参数）</span> </span></span><span style="display:flex;"><span>qm shutdown &lt;vmid&gt; </span></span><span style="display:flex;"><span>qm start &lt;vmid&gt; </span></span></code></pre></div><p>首次启动后 QEMU 命令行会变为类似：</p>