Basic volume quality of service

Basic volume QoS allows you to define hard performance limits for volumes on a per-volume basis.

Performance parameters for attached volumes are controlled using volume types and associated extra-specs.

As of the 13.0.0 Rocky release, Cinder supports the following options to control volume quality of service, the values of which should be fairly self-explanatory:

For Fixed IOPS per volume.

  • read_iops_sec

  • write_iops_sec

  • total_iops_sec

For Burst IOPS per volume.

  • read_iops_sec_max

  • write_iops_sec_max

  • total_iops_sec_max

For Fixed bandwidth per volume.

  • read_bytes_sec

  • write_bytes_sec

  • total_bytes_sec

For Burst bandwidth per volume.

  • read_bytes_sec_max

  • write_bytes_sec_max

  • total_bytes_sec_max

For burst bucket size.

  • size_iops_sec

Note that the total_* and total_*_max options for both iops and bytes cannot be used with the equivalent read and write values.

For example, in order to create a QoS extra-spec with 20000 read IOPs and 10000 write IOPs, you might use the Cinder client in the following way:

$ cinder qos-create high-iops consumer="front-end" \
  read_iops_sec=20000 write_iops_sec=10000
+----------+--------------------------------------+
| Property | Value                                |
+----------+--------------------------------------+
| consumer | front-end                            |
| id       | f448f61c-4238-4eef-a93a-2024253b8f75 |
| name     | high-iops                            |
| specs    | read_iops_sec : 20000                |
|          | write_iops_sec : 10000               |
+----------+--------------------------------------+

The equivalent OpenStack client command would be:

$ openstack volume qos create --consumer "front-end" \
  --property "read_iops_sec=20000" \
  --property "write_iops_sec=10000" \
  high-iops

Once this is done, you can associate this QoS with a volume type by using the qos-associate Cinder client command.

$ cinder qos-associate QOS_ID VOLUME_TYPE_ID

or using the openstack volume qos associate OpenStack client command.

$ openstack volume qos associate QOS_ID VOLUME_TYPE_ID

You can now create a new volume and attempt to attach it to a consumer such as Nova. If you login to the Nova compute host, you’ll be able to see the assigned limits when checking the XML definition of the virtual machine with virsh dumpxml.

Note

As of the Nova 18.0.0 Rocky release, front end QoS settings are only supported when using the libvirt driver.