{"id":10622,"date":"2026-01-08T10:00:23","date_gmt":"2026-01-08T09:00:23","guid":{"rendered":"https:\/\/www.credativ.de\/?p=10622"},"modified":"2026-01-08T10:00:23","modified_gmt":"2026-01-08T09:00:23","slug":"determining-the-maximum-cpu-model-for-live-migrations-in-proxmox-clusters-with-proxclmc","status":"publish","type":"post","link":"https:\/\/www.credativ.de\/en\/blog\/howtos-en\/determining-the-maximum-cpu-model-for-live-migrations-in-proxmox-clusters-with-proxclmc\/","title":{"rendered":"Determining the Maximum CPU Model for Live Migrations in Proxmox Clusters with ProxCLMC"},"content":{"rendered":"

ProxCLMC \u2013 What is it?<\/strong><\/h2>\n

Live migration is one of the most powerful and frequently used functions in a Proxmox VE Cluster<\/a>. However, it presupposes a requirement that is often underestimated: consistent CPU compatibility across all nodes. In real-world environments, clusters rarely consist of identical hardware where you could simply use the CPU type host<\/em><\/a>. Nodes are added over time, CPU generations differ, and functional scopes continue to evolve. Although Proxmox VE allows a flexible CPU configuration, determining a safe and optimal CPU baseline for the entire cluster has so far been largely a manual and experience-based task. <\/p>\n

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ProxCLMC<\/a> (Prox CPU Live Migration Checker) was developed by our colleague Florian Paul Azim Hoberg (also known as gyptazy<\/a>) in Rust as an open-source solution under the GPLv3 license to close this gap<\/a> in a simple, automated, and reproducible way. The tool examines all nodes of a Proxmox VE cluster, subsequently analyzes their CPU capabilities, and calculates the highest possible CPU compatibility level supported by each node. Instead of relying on assumptions, spreadsheets, or trial and error, administrators receive a clear and deterministic result that can be used directly when selecting VM CPU models. <\/p>\n

Comparable mechanisms already exist in other virtualization ecosystems. Enterprise platforms often offer integrated tools or automatic assistance to detect compatible CPU baselines and prevent invalid live migration configurations. Proxmox VE<\/a> currently does not have such an automated detection mechanism, so administrators must manually compare CPU flags or rely on operational experience. ProxCLMC<\/strong> closes this gap by providing a cluster-wide CPU compatibility analysis specifically tailored to Proxmox environments. <\/p>\n

How does ProxCLMC work?<\/h2>\n

ProxCLMC<\/a> is designed to integrate seamlessly into existing Proxmox VE clusters without requiring additional services, agents, or configuration changes. It is written entirely in Rust (fully open source under GPLv3), compiled as a static binary, and provided as a Debian package via the gyptazy repository to facilitate easy installation. The workflow follows a clear and transparent process that reflects how administrators think about CPU compatibility but automates it reliably and reproducibly. <\/p>\n

After starting, the tool parses the local corosync.conf<\/code> on the node on which it is running. This allows ProxCLMC to automatically detect all members of the cluster without relying on external inventories or manual input. The determined node list thus always corresponds to the actual state of the cluster. <\/p>\n

Once all cluster nodes are identified, ProxCLMC establishes an SSH connection to each node. Via this connection, it remotely reads the content of \/proc\/cpuinfo<\/code>. This file provides a detailed and authoritative view of the CPU capabilities provided by the host kernel, including the complete set of supported CPU flags. <\/p>\n

From the collected data, ProxCLMC extracts the relevant CPU flags and evaluates them based on clearly defined x86-64 CPU baseline definitions. These baselines are directly based on the CPU models supported by Proxmox VE and QEMU, including: <\/p>\n