Environment
XCP-ng version: 8.3 (latest)
Xen Orchestra (XO): Build 202606261855
Pool topology: 2-node pool ("Olympus")
Host A (master, Zeus): 128 GB RAM, 7 VMs running (~34 GB allocated)
Host B (slave, Hera): 64 GB RAM, 4 VMs running (~32 GB allocated)
HA: Enabled, ha-host-failures-to-tolerate = 0, ha-overcommitted = false
Storage: Shared NFS SRs (all VMs on shared storage — no local-SR VMs)
What I'm trying to do
Test planned maintenance / HA evacuation: reboot Host B (Hera) via Xen Orchestra, expecting its running VMs to live-migrate to Host A (Zeus) automatically.
What happens
The host.restart call from XO (with suspendResidentVms: false, bypassCurrentVmCheck: false) fails immediately with:
HOST_NOT_ENOUGH_FREE_MEMORY(OpaqueRef:<vm-ref>)
Full task error:
{
"error_info": [
"HOST_NOT_ENOUGH_FREE_MEMORY",
"OpaqueRef:<vm-opaque-ref>"
],
"name": "XapiError",
"message": "HOST_NOT_ENOUGH_FREE_MEMORY(OpaqueRef:<vm-opaque-ref>)",
"stack": "XapiError: HOST_NOT_ENOUGH_FREE_MEMORY(OpaqueRef:<vm-opaque-ref>)\n at XapiError.wrap (file:///opt/xo/xo-builds/.../packages/xen-api/_XapiError.mjs:16:12)\n at default
(file:///opt/xo/xo-builds/.../packages/xen-api/_getTaskResult.mjs:13:29)\n ..."
}
Backtrace points to ocaml/xapi/xapi_host.ml:629 inside Async.host.evacuate.
The same error is produced when running xe host-evacuate directly on the pool master:
Not enough server memory is available to perform this operation.
needed: <vm-uuid> (<VM name>)
available: <unknown>
Note the available: <unknown> — XCP-ng cannot determine the available memory on the destination host.
Actual memory figures from xe host-list params=memory-free,memory-total,memory-overhead:
┌────────────────────────┬───────────┬──────────┬──────────┐
│ Host │ Total RAM │ Free RAM │ Overhead │
├────────────────────────┼───────────┼──────────┼──────────┤
│ Zeus (destination) │ 128 GB │ 84.7 GB │ 1.58 GB │
├────────────────────────┼───────────┼──────────┼──────────┤
│ Hera (being evacuated) │ 64 GB │ 26.5 GB │ 0.93 GB │
└────────────────────────┴───────────┴──────────┴──────────┘
VMs on Hera that need to migrate:
┌───────┬──────────────────┬─────────────────┐
│ VM │ RAM (static-max) │ memory-overhead │
├───────┼──────────────────┼─────────────────┤
│ VM-1 │ 12 GB │ 106 MB │
├───────┼──────────────────┼─────────────────┤
│ VM-2 │ 8 GB │ 74 MB │
├───────┼──────────────────┼─────────────────┤
│ VM-3 │ 8 GB │ 74 MB │
├───────┼──────────────────┼─────────────────┤
│ VM-4 │ 4 GB │ 36 MB │
├───────┼──────────────────┼─────────────────┤
│ Total │ 32 GB │ 290 MB │
└───────┴──────────────────┴─────────────────┘
Zeus has 84.7 GB free. The VMs need ~32.3 GB (RAM + overhead). There is 52 GB of headroom. The error should not occur.
Any help appreciated — this makes planned host maintenance require manual CLI steps every time, which defeats the purpose of the evacuate-on-reboot workflow.
