Documentation Index
Fetch the complete documentation index at: https://docs.xloud.tech/llms.txt
Use this file to discover all available pages before exploring further.
Overview
Live vCPU and RAM scaling lets you adjust the compute resources of a running instance without rebooting. Changes take effect immediately while the instance continues serving traffic. The Dashboard provides a slider-based dialog for intuitive scaling within the bounds configured on the instance’s flavor.Xloud-Developed — Bidirectional CPU hotplug (add AND remove vCPUs) and combined memory scaling (balloon + DIMM + virtio-mem) are developed by Xloud and ship with XAVS / XPCI.
Prerequisites
- Instance must be in
Activestatus - The instance must not be locked
- The flavor must have hot-add enabled (
hw:cpu_minorhw:mem_minextra specs) — if you do not see Adjust Resources in the actions menu, the flavor does not support live scaling
Scale vCPU or RAM
- Dashboard
- CLI
Open the Resource Adjustment dialog
Navigate to Compute > Instances. Click the More dropdown on
the instance row, then select Adjust Resources under the
Configuration Update group.
This action only appears for instances in
Active status whose flavor
has hot-add enabled. If you do not see it, contact your administrator
to configure a hot-add-enabled flavor.Adjust resources with sliders
The dialog shows the current state and adjustment controls:
The dialog fetches the live instance status to determine the current and
allowed resource ranges. Color-coded hints indicate the scaling method:
| Field | Description |
|---|---|
| Instance | Instance name (read-only) |
| Current Info | Current vCPU count and memory allocation (read-only) |
| vCPUs | Slider input — drag or type to set between minimum and maximum vCPUs |
| Memory (GiB) | Slider input — adjust between minimum and maximum memory in 0.25 GiB steps |
| Make permanent | Checkbox — persist the configuration after a soft reboot (default: checked) |
| Color | Meaning |
|---|---|
| Green | virtio-mem — fully adjustable in both directions |
| Yellow | No balloon driver detected — limited memory scaling |
| Blue | DIMM hotplug information |
Comparison: Live Scaling vs. Flavor Resize
| Live vCPU/RAM Scaling | Flavor Resize | |
|---|---|---|
| Downtime | None — instance stays running | Reboot required |
| Scope | vCPU and RAM only | vCPU, RAM, and disk |
| Direction | Up or down within flavor envelope | Up or down (disk: up only) |
| Confirmation step | No — instant | Yes — must confirm or revert |
| Dashboard action | More > Configuration Update > Adjust Resources | More > Configuration Update > Resize |
| Use case | Responding to live load changes | Permanent tier change |
Troubleshooting
Adjust Resources not visible in the menu
Adjust Resources not visible in the menu
Scaling request rejected
Scaling request rejected
The requested value is outside the allowed range. The minimum and maximum are
determined by the flavor’s
hw:cpu_min / hw:mem_min (minimum) and the flavor’s
vCPUs / RAM (maximum). Try a value within the slider range.Guest OS does not show new vCPUs
Guest OS does not show new vCPUs
On older Linux kernels (before 4.15), new CPUs may need to be brought online manually:Modern kernels (4.15+) bring CPUs online automatically.
Bring hotplugged CPUs online
Memory change has no effect
Memory change has no effect
The guest OS memory balloon driver may not be loaded. Check inside the guest:If not loaded:
Check balloon driver
modprobe virtio_balloon and add virtio_balloon to /etc/modules
for persistence.Next Steps
Admin: Enable Live Scaling
Configure flavors with hot-add extra specs and resource bounds
Resize Instance
Standard flavor resize — change vCPU, RAM, and disk with a reboot
Flavors
View available flavors and their hot-add capabilities
Launch an Instance
Create an instance with a hot-add-enabled flavor