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Taikun OCP Guide

Table of Contents

Manage Flavors

Admin users can use the openstack flavor command to customize and manage
flavors. To see information for this command, run:

$ openstack flavor --help
Command "flavor" matches:
  flavor create
  flavor delete
  flavor list
  flavor set
  flavor show
  flavor unset


Configuration rights can be delegated to additional users by
redefining the access controls for
os_compute_api:os-flavor-manage:update and
os_compute_api:os-flavor-manage:delete in
/etc/nova/policy.yaml on the nova-api


Flavor customization can be limited by the hypervisor in use. For
example the libvirt driver enables quotas on CPUs available to a VM,
disk tuning, bandwidth I/O, watchdog behavior, random number generator
device control, and instance VIF traffic control.

For information on the flavors and flavor extra specs, refer to /user/flavors.

Create a flavor

  1. List flavors to show the ID and name, the amount of memory, the
    amount of disk space for the root partition and for the ephemeral
    partition, the swap, and the number of virtual CPUs for each flavor:

    $ openstack flavor list
  2. To create a flavor, specify a name, ID, RAM size, disk size, and
    the number of vCPUs for the flavor, as follows:

    $ openstack flavor create FLAVOR_NAME --id FLAVOR_ID \
        --ram RAM_IN_MB --disk ROOT_DISK_IN_GB --vcpus NUMBER_OF_VCPUS


    Unique ID (integer or UUID) for the new flavor. If specifying ‘auto’,
    a UUID will be automatically generated.

    Here is an example that creates a public m1.extra_tiny
    flavor that automatically gets an ID assigned, with 256 MB memory, no
    disk space, and one VCPU.

    $ openstack flavor create --public m1.extra_tiny --id auto \
        --ram 256 --disk 0 --vcpus 1
  3. If an individual user or group of users needs a custom flavor
    that you do not want other projects to have access to, you can create a
    private flavor.

    $ openstack flavor create --private m1.extra_tiny --id auto \
        --ram 256 --disk 0 --vcpus 1

    After you create a flavor, assign it to a project by specifying the
    flavor name or ID and the project ID:

    $ openstack flavor set --project PROJECT_ID m1.extra_tiny

    For a list of optional parameters, run this command:

    $ openstack help flavor create
  4. In addition, you can set or unset properties, commonly referred
    to as “extra specs”, for the existing flavor. The
    extra_specs metadata keys can influence the instance
    directly when it is launched. If a flavor sets the
    quota:vif_outbound_peak=65536 extra spec, the instance’s
    outbound peak bandwidth I/O should be less than or equal to 512 Mbps.
    There are several aspects that can work for an instance including
    CPU limits, Disk tuning, Bandwidth I/O,
    Watchdog behavior, and Random-number generator. For
    information about available metadata keys, see /user/flavors.

    For a list of optional parameters, run this command:

    $ openstack flavor set --help

Modify a flavor

Only the description of flavors can be modified (starting from
microversion 2.55). To modify the description of a flavor, specify the
flavor name or ID and a new description as follows:

$ openstack --os-compute-api-version 2.55 flavor set --description <DESCRIPTION> <FLAVOR>


The only field that can be updated is the description field. Nova has
historically intentionally not included an API to update a flavor
because that would be confusing for instances already created with that
flavor. Needing to change any other aspect of a flavor requires deleting
and/or creating a new flavor.

Nova stores a serialized version of the flavor associated with an
instance record in the instance_extra table. While nova
supports updating
flavor extra_specs
it does not update the embedded flavor in
existing instances. Nova does not update the embedded flavor as the
extra_specs change may invalidate the current placement of the instance
or alter the compute context that has been created for the instance by
the virt driver. For this reason admins should avoid updating
extra_specs for flavors used by existing instances. A resize can be used
to update existing instances if required but as a resize performs a cold
migration it is not transparent to a tenant.

Delete a flavor

To delete a flavor, specify the flavor name or ID as follows:

$ openstack flavor delete FLAVOR

Default Flavors

Previous versions of nova typically deployed with default flavors.
This was removed from Newton. The following table lists the default
flavors for Mitaka and earlier.

Flavor VCPUs Disk (in GB) RAM (in MB)






















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