Another feature provided by Cinder is the ability to define and manage classes of service for volumes. Like volume encryption, Quality of Service (QoS) in Cinder is configured by volume type. By default, you can define values for minimum, maximum, and burst IOPS.
To configure volume QoS, you will need the following information:
- An
openrcfile with appropriate credentials for the environment (you need to be an administrator) - The
openstackcommand-line client - The name or ID of the volume type
- The consumer of the QoS policy
- Values for the following:
- Minimum IOPS
- Maximum IOPS
- Burst IOPS
For our example, these will be as follows:
- Name:
High IOPS - Consumer:
both - Maximum IOPS:
500
For Cinder volumes to use QoS, an administrator needs to perform two steps: first, define the specification, and second, to associate the specification with a volume type.
To create and assign a QoS specification, use the following steps:
- First, list the existing QoS specifications:
openstack volume qos list --print-emptyWe currently don't have any QoS defined:
- Define a new QoS specification with the following:
openstack volume qos create --consumer both --property maxIOPS=500 "High IOPS"
This will bring back the following output:
- Confirm our QoS specification was created by listing the QoS available:
openstack volume qos list -c Name -c Consumer -c Properties -f tableThis will bring back the following output:
- We now associate the policy to a volume type as follows:
openstack volume qos associate "High IOPS" "High IOPS"
QoS specifications are defined within Cinder using the openstack volume qos set of commands. When creating a QoS specification, you can specify where QoS is applied as well as the value to set it at. Currently, you can specify a static set of minimum, maximum, and burst IOPS, and a scaling set of IOPS.
The static values break down as follows:
- Minimum IOPS: This is the number of IOPs guaranteed to a volume
- Maximum: This is the ceiling for IOPS on a volume
- Burst IOPS: This is the maximum IOPS over a short period
Scaling IOPs then, define the amount to change the static values for each additional gigabyte of volume size.