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--- virtualisation:proxmox_ve:known_bugs_in_proxmox_ve_9 [2026/04/14 20:12] – removed - external edit (Unknown date) 127.0.0.1
+++ virtualisation:proxmox_ve:known_bugs_in_proxmox_ve_9 [2026/04/14 20:12] (current) – ↷ Page moved from virtualisation:proxmox_ve:vms_cts:known_bugs_in_proxmox_ve_9 to virtualisation:proxmox_ve:known_bugs_in_proxmox_ve_9 thum
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+====== Known Bugs and Quirks in Proxmox VE ≥ 9 ======
+===== Changes Proxmox VE 8 to Proxmox VE 9 =====
+Please note the official upgrade comments: [[https://pve.proxmox.com/wiki/Upgrade_from_8_to_9]]
+===== Proxmox VE 9: VM RAM Usage Displayed Higher Than Actual =====
+==== Background ====
+  * Official documentation: [[https://pve.proxmox.com/wiki/Upgrade_from_8_to_9#VM_Memory_Consumption_Shown_is_Higher|Proxmox Upgrade 8 to 9 – VM Memory Consumption Shown is Higher]]
+  * Confirmed in forum: [[https://forum.proxmox.com/threads/memory-usage-wrong-on-freebsd-guests-9-0-3.169690/|Memory usage wrong on FreeBSD guests – 9.0.3]]
+==== What Changed in Proxmox 9 ====
+In **PVE 9**, VMs that do not report memory usage via the ballooning mechanism — as well as ''*BSD'' VMs due to an incomplete balloon driver implementation — now display the **host-side RAM allocation** rather than the actual usage reported by the guest.
+This is a deliberate change from PVE 8, where the host-side RSS of the ''kvm'' process was shown instead.
+==== Clarification: FreeBSD is a Special Case ====
+The issue for FreeBSD is **not** that the balloon driver may be missing.  Even if the ''vtballoon'' driver is present and active (verifiable via ''sysctl dev.vtballoon''),  the problem is more specific:
+<note>
+FreeBSD's ''vtballoon'' driver does **not** implement ''VIRTIO_BALLOON_F_STATS_VQ'' — the virtio feature that sends memory usage statistics back to the hypervisor. The driver can respond to balloon inflate/deflate requests from the host, but never actively reports memory usage data.
+</note>
+This is an open bug in FreeBSD:
+  * [[https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292570|FreeBSD Bug #292570]] — "virtio-balloon does not balloon correctly" (still open as of 2026)
+=== Windows ===
+This differs from Windows without the VirtIO BalloonService, where the driver is entirely absent. On FreeBSD, the driver exists but is functionally incomplete with respect to what Proxmox VE expects.
+==== Affected VM Types ====
+^ Guest OS ^ Reason ^ Driver Status ^
+| FreeBSD / OPNsense / pfSense | ''VIRTIO_BALLOON_F_STATS_VQ'' not implemented | Driver present, stats reporting missing |
+| Windows (without VirtIO BalloonService) | Balloon driver not installed | Driver absent |
+| Any VM with ''balloon: 0'' | Ballooning explicitly disabled | N/A |
+==== Practical Impact ====
+  * No impact on stability or VM operation
+  * RAM usage in the Proxmox VE GUI and API is misleading for affected VMs
+  * Dynamic memory reclamation (balloon deflation) by the host does not work reliably for FreeBSD guests
+  * Risk of unexpected OOM conditions on the host if memory pressure is high and FreeBSD VMs cannot be deflated
+==== What to do? ====
+  * Disable ballooning for FreeBSD VMs (since it does not function correctly anyway): //'# qm set <vmid> --balloon 0'//
+  * Use //proxmox-rmem// — a community tool that reads guest-reported memory and surfaces it correctly: [[https://github.com/IT-BAER/proxmox-rmem|proxmox-rmem on Github]]
+  * Monitor via external tooling such as LibreNMS, Prometheus + node_exporter or Zabbix, deployed inside the FreeBSD VM
+  * Read actual guest memory usage via the QEMU Guest Agent (see next chapter):
+===== FreeBSD VM Memory Analysis via QEMU Guest Agent =====
+==== Background ====
+When running FreeBSD as a Proxmox/QEMU guest with virtio-balloon enabled, the reported RAM usage in the Proxmox VE GUI is often misleading. This documents how to query actual memory usage directly from the guest using ''qm guest exec''.
+==== Querying Memory Stats ====
+Run the following on the Proxmox node where the VM resides.  As an example we use an OPNsense 14.3 VM (VM ID 100) on Proxmox VE 9.1.6 (node 'n3'):
+<code>
+qm guest exec 100 -- sh -c "sysctl -n \
+  vm.stats.vm.v_page_count \
+  vm.stats.vm.v_active_count \
+  vm.stats.vm.v_inactive_count \
+  vm.stats.vm.v_wire_count \
+  vm.stats.vm.v_free_count \
+  vm.stats.vm.v_cache_count \
+  vm.stats.vm.v_page_size"
+</code>
+**Important:** Run this command on the correct node. If the VM lives on node ''n3'', you must be logged into ''n3''. Otherwise you will get:
+<code>
+Configuration file 'nodes/n3/qemu-server/110.conf' does not exist
+</code>
+==== Example Output & Interpretation ====
+Example raw output (''out-data''):
+<code>
+2018895\n15672\n64009\n123634\n1812399\n0\n4096
+</code>
+^ sysctl Key            ^ Pages     ^ MB      ^ %      ^ Notes                        ^
+| v_page_count (Total)  | 2,018,895 | 7,886 MB | 100%  | Total RAM assigned to VM     |
+| v_active_count        | 15,672    | 61 MB    | 0.8%  | Currently in active use      |
+| v_inactive_count      | 64,009    | 250 MB   | 3.2%  | Reclaimable, not active      |
+| v_wire_count          | 123,634   | 483 MB   | 6.1%  | Kernel/wired, non-reclaimable |
+| v_free_count          | 1,812,399 | 7,080 MB | 89.8% | Truly free pages             |
+| v_cache_count         | 0         | 0 MB     | 0%    | ⚠️ See note below            |
+**Calculation formulas:**
+  * Total MB = ''v_page_count × v_page_size / 1024²''
+  * Effectively used MB = ''(v_active_count + v_wire_count) × v_page_size / 1024²''  → ~544 MB (6.9%)
+  * Available MB = ''(v_free_count + v_inactive_count + v_cache_count) × v_page_size / 1024²''  → ~7,330 MB (92.9%)
+==== The Ballooning Problem ====
+=== v_cache_count = 0 ===
+Normally FreeBSD fills the page cache aggressively. A value of ''0'' for ''v_cache_count'' indicates that the **virtio-balloon driver is not properly returning unused pages to the hypervisor**. This is a known FreeBSD bug ([[https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277473|FreeBSD Bug #277473]]).
+=== Why Proxmox Shows Wrong RAM Usage ===
+Proxmox derives the displayed RAM usage from the **balloon driver** (virtio-balloon), not from the guest agent. The balloon driver reports how much RAM the VM currently "holds" (the ''actual'' balloon value), not real consumption. This causes Proxmox to display 2–3× higher RAM usage than the guest actually needs.
+=== Summary ===
+^ Metric                  ^ Value    ^
+| Effectively used RAM    | ~544 MB  |
+| Proxmox-reported RAM    | ~7.7 GB  |
+| Discrepancy factor      | ~14×     |