Flavor Management

Overview

Flavors define the virtual hardware profile for instances — vCPU count, memory allocation, root disk size, and optional hardware extensions. Every instance must be launched with a flavor. Administrators control the flavor catalog available to all tenants, and can create private flavors restricted to specific projects for tailored workload sizing.

Administrator Access Required — This operation requires the admin role. Contact your Xloud administrator if you do not have sufficient permissions.

Prerequisites

Admin credentials sourced from admin-openrc.sh
openstack CLI installed and configured

Default Flavors

The following flavors are available in a standard Xloud Compute deployment.

Flavor	vCPUs	RAM	Root Disk	Use Case
`m1.tiny`	1	512 MB	1 GB	Lightweight agents, minimal workloads
`m1.small`	1	2 GB	20 GB	Development, testing
`m1.medium`	2	4 GB	40 GB	General-purpose applications
`m1.large`	4	8 GB	80 GB	Web servers, mid-tier services
`m1.xlarge`	8	16 GB	160 GB	Databases, compute-intensive workloads

Create, Modify, and Delete Flavors

Dashboard
CLI

Open flavor management

Create a flavor

Click Create Flavor and fill in the required fields:

Field	Description
Name	Unique identifier (e.g., `c4.2xlarge`)
vCPUs	Virtual CPU count
RAM (MB)	Memory in megabytes
Root Disk (GB)	Size of the instance root disk
Ephemeral Disk (GB)	Optional local scratch disk, discarded when instance is deleted
Swap (MB)	Optional swap partition size
Public	Toggle off to restrict access to specific projects

Click Create Flavor to save.

The new flavor appears in the flavor list and is immediately available for instance launches.

Modify extra specs

Click the flavor name to open its detail view. Navigate to the Extra Specs tab to add hardware hints such as CPU pinning policy, huge page requirements, or NUMA topology constraints.Click Add Extra Spec, enter the key and value, and click Save.

Delete a flavor

In the flavor list, open the Actions menu for the target flavor and select Delete Flavor. Confirm the deletion.

Deleting a flavor does not affect running instances using it. Instances retain their original hardware profile until they are rebuilt or resized.

Authenticate

Source your credentials file to authenticate with the Xloud platform:

Load credentials

source admin-openrc.sh

Download the OpenRC file from Xloud Dashboard → Project → API Access → Download OpenStack RC File.

Create a flavor

Create a custom flavor

openstack flavor create \
  --vcpus 4 \
  --ram 8192 \
  --disk 80 \
  --public \
  c4.large

Add extra specs

Extra specs pass hardware hints directly to the hypervisor. Set CPU pinning and huge page requirements on a flavor:

Set CPU pinning policy

openstack flavor set c4.large \
  --property hw:cpu_policy=dedicated \
  --property hw:mem_page_size=1GB

List all extra specs on a flavor to verify:

Show flavor extra specs

openstack flavor show c4.large -f json | python3 -c \
  "import sys,json; d=json.load(sys.stdin); print(d.get('properties',''))"

Create a private flavor

Restrict a flavor to one or more specific projects using the private flavor pattern:

Make flavor private and grant project access

openstack flavor set --no-public c4.large
openstack flavor access add --project <project-id> c4.large

Private flavors are visible only to the project they are granted to. Use this pattern to offer specialized instance sizes (GPU, high-memory) to specific customers without exposing them to all tenants.

Delete a flavor

Delete flavor

openstack flavor delete c4.large

Confirm deletion with openstack flavor list — the flavor should no longer appear.

Extra Specs Reference

Extra specs are key-value properties on a flavor that control hypervisor-level behavior. The following table lists commonly used extra specs.

Key	Values	Description
`hw:cpu_policy`	`dedicated`, `shared`	`dedicated` pins vCPUs to exclusive physical threads
`hw:cpu_thread_policy`	`prefer`, `isolate`, `require`	Controls NUMA thread sibling usage
`hw:mem_page_size`	`small`, `large`, `1GB`, `2MB`	Requests huge pages for the instance
`hw:numa_nodes`	Integer	Number of NUMA nodes to expose inside the instance
`hw:tpm_version`	`1.2`, `2.0`	Enables virtual TPM with specified version
`hw:tpm_model`	`tpm-tis`, `tpm-crb`	Virtual TPM hardware model
`os:secure_boot`	`required`, `optional`, `disabled`	Controls UEFI Secure Boot policy
`pci_passthrough:alias`	`<alias>:<count>`	Requests PCI device passthrough by alias name
`hw:cpu_max_sockets`	Integer	Max vCPU socket ceiling for live scaling
`hw:cpu_max_cores`	Integer	Cores per socket for live scaling envelope
`hw:cpu_max_threads`	Integer	Threads per core for live scaling envelope
`hw:mem_max_mb`	Integer	Max RAM (MB) ceiling for live scaling
`aggregate_instance_extra_specs:<key>`	Any string	Match against host aggregate metadata for scheduling

Extra specs that reference hardware features (CPU pinning, huge pages, PCI passthrough) require the corresponding scheduler filter to be active. See Scheduling for the full filter list.

Flavor Metadata (User-Visible Tags)

Flavor (also called flavor tags) are display-layer annotations. Unlike extra specs, they do not influence the scheduler or hypervisor. Use them to communicate workload guidance, compliance designations, or SLA tiers to end users.

Dashboard
CLI

Open flavor metadata editor

Navigate to Admin → Compute → Flavors. In the flavor row, open Actions → Update Metadata.

Add metadata entries

In the Available Metadata panel, type a custom key (or select from a registered namespace) and enter its value. Click + to add each entry.

Example Key	Example Value	Purpose
`sla_tier`	`gold`	Communicate SLA level to users
`workload`	`database`	Hint recommended use case
`compliance`	`pci-dss`	Tag for regulated workloads
`gpu`	`v100`	Indicate GPU availability
`cost_category`	`high-memory`	Billing/chargeback classification

Save

Click Save. Metadata is immediately visible in the flavor detail view and API responses.

Set flavor metadata (tags)

openstack flavor set m1.large \
  --property sla_tier=gold \
  --property workload=database \
  --property compliance=pci-dss

List flavor metadata

openstack flavor show m1.large -c properties

Remove a metadata key

openstack flavor unset m1.large --property sla_tier

Metadata vs Extra Specs

Feature	Metadata (Tags)	Extra Specs
Affects scheduling	No	Yes (via scheduler filters)
Affects hypervisor	No	Yes (CPU pinning, huge pages, etc.)
Visible to users	Yes	Admin-facing
Use for	Display labels, compliance tags, cost categories	Hardware configuration, placement control

Next Steps

Advanced Features

Use extra specs to enable CPU pinning, huge pages, GPU passthrough, and vTPM.

Quota Management

Set per-project resource ceilings that govern how many flavors a tenant can deploy.

Admin Guide

Return to the Compute Administration Guide index.

Core Services

Other Services

Flavor Management

Overview

Default Flavors

Create, Modify, and Delete Flavors

Open flavor management

Create a flavor

Modify extra specs

Delete a flavor

Authenticate

Create a flavor

Add extra specs

Create a private flavor

Delete a flavor

Extra Specs Reference

Flavor Metadata (User-Visible Tags)

Open flavor metadata editor

Add metadata entries

Save

Metadata vs Extra Specs

Next Steps

Advanced Features

Quota Management

Admin Guide

Core Services

Other Services

​Overview

​Default Flavors

​Create, Modify, and Delete Flavors

Open flavor management

Create a flavor

Modify extra specs

Delete a flavor

Authenticate

Create a flavor

Add extra specs

Create a private flavor

Delete a flavor

​Extra Specs Reference

​Flavor Metadata (User-Visible Tags)

Open flavor metadata editor

Add metadata entries

Save

​Metadata vs Extra Specs

​Next Steps

Advanced Features

Quota Management

Admin Guide

Overview

Default Flavors

Create, Modify, and Delete Flavors

Extra Specs Reference

Flavor Metadata (User-Visible Tags)

Metadata vs Extra Specs

Next Steps