openstack-manuals/doc/user-guide-admin/source/cli_manage_flavors.rst

Manage flavors

In OpenStack, flavors define the compute, memory, and storage capacity of nova computing instances. To put it simply, a flavor is an available hardware configuration for a server. It defines the "size" of a virtual server that can be launched.

Note

Flavors can also determine on which compute host a flavor can be used to launch an instance. For information about customizing flavors, refer to the OpenStack Cloud Administrator Guide.

A flavor consists of the following parameters:

Flavor ID

Automatically generated by OpenStack. For private flavors, a value from 1 to 255.

Name

Name for the new flavor.

VCPUs

Number of virtual CPUs to use.

Memory MB

Amount of RAM to use (in megabytes).

Root Disk GB

Amount of disk space (in gigabytes) to use for the root (/) partition.

Ephemeral Disk GB

Amount of disk space (in gigabytes) to use for the ephemeral partition. If unspecified, the value is 0 by default. Ephemeral disks offer machine local disk storage linked to the life cycle of a VM instance. When a VM is terminated, all data on the ephemeral disk is lost. Ephemeral disks are not included in any snapshots.

Swap

Amount of swap space (in megabytes) to use. If unspecified, the value is 0 by default.

The default flavors are:

Flavor	VCPUs	Disk (in GB)	RAM (in MB)
m1.tiny	1	1	512
m1.small	1	20	2048
m1.medium	2	40	4096
m1.large	4	80	8192
m1.xlarge	8	160	16384

You can create and manage flavors with the nova flavor-* commands provided by the python-novaclient package.

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:

   $ nova 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:

   $ nova flavor-create FLAVOR_NAME FLAVOR_ID RAM_IN_MB ROOT_DISK_IN_GB NUMBER_OF_VCPUS

   Note

   The flavor ID is a number from 1 to 255 and cannot contain special characters or spaces.

   Here is an example with additional optional parameters filled in that creates a public extra tin flavor that automatically gets an ID assigned, with 256 MB memory, no disk space, and one VCPU. The rxtx-factor indicates the slice of bandwidth that the instances with this flavor can use (through the Virtual Interface (vif) creation in the hypervisor):

   $ nova flavor-create --is-public true m1.extra_tiny auto 256 0 1 --rxtx-factor .1

3. If an individual user or group of users needs a custom flavor that you do not want other tenants to have access to, you can change the flavor's access to make it a private flavor. See Private Flavors in the OpenStack Operations Guide.

   For a list of optional parameters, run this command:

   $ nova help flavor-create

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

   $ nova flavor-access-add FLAVOR TENANT_ID

5. In addition, you can set or unset extra_spec for the existing flavor. The extra_spec metadata keys can influence the instance directly when it is launched. If a flavor sets the extra_spec key/value quota:vif_outbound_peak=65536, the instance's out bound peak bandwidth I/O should be LTE 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 supporting metadata keys, see the OpenStack Cloud Administrator Guide.

   For a list of optional parameters, run this command:

   $ nova help flavor-key

Delete a flavor

Delete a specified flavor, as follows:

$ nova flavor-delete FLAVOR_ID