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Taikun OCP Guide

Table of Contents

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.

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