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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 adjusts an instance’s compute resources while it is running — no reboot required. This is distinct from the standard resize operation, which requires a reboot. Live scaling uses a combination of CPU hotplug, memory balloon, DIMM hotplug, and virtio-mem to adjust resources within the bounds defined by 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
  • An instance in Active status with a hot-add-enabled flavor
  • The flavor must have hw:cpu_min or hw:mem_min extra specs set
  • The instance must not be locked

Adjust Resources (Dashboard)

1

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 is only available for instances in Active status whose flavor has hot-add enabled (hw:cpu_min or hw:mem_min extra specs). If the flavor does not support hot-add, this action does not appear.
2

Adjust vCPU and memory

The dialog shows:
FieldDescription
InstanceInstance name (read-only)
Current InfoCurrent vCPU count and memory allocation (read-only)
vCPUsSlider input — adjust between minimum and maximum vCPUs
Memory (GiB)Slider input — adjust between minimum and maximum memory (0.25 GiB steps)
Make permanentCheckbox — persist the configuration after a soft reboot (default: checked)
The vCPU slider step aligns to the CPU thread count configured in the flavor. The memory slider uses 0.25 GiB increments.The dialog fetches the live instance status to determine current and allowed resource ranges. Color-coded hints indicate the scaling method:
ColorMeaning
Greenvirtio-mem — fully adjustable in both directions
YellowNo balloon driver detected — limited scaling
BlueDIMM hotplug information
3

Apply the adjustment

Click Confirm. The resources are adjusted immediately while the instance continues running.
Instance vCPU and memory updated in real-time. Verify from the instance detail page or by running nproc / free -h inside the guest.

Configure Hot-Add Flavors

To enable live scaling, create flavors with hot-add parameters:
When creating a flavor (see Flavor Management), enable the Hot-Add toggle in the Step 1 (Params Setting) section. Configure:
FieldDescription
Enable Hot-AddSet to Yes
Minimum CPUStarting vCPU count at boot (can scale up to flavor’s max vCPUs)
Minimum Memory (GiB)Starting memory at boot (can scale up to flavor’s max memory)
The instance boots with the minimum resources and can be scaled up to the flavor’s maximum without rebooting.

Next Steps

Resize an Instance

Change flavors entirely (requires reboot) for capacity beyond hot-add range

Flavors

Create and manage flavors with hot-add configuration

Launch an Instance

Launch instances with hot-add enabled flavors

Troubleshooting

Resolve live scaling failures and balloon driver issues