As with CPU limits, IOPS limits can also be imposed to prevent an instance type from hogging all of the available IO on a system. IOPS here refers to the storage and network IO. Also, as with CPU limits, IOPS limits are a special case of flavor attributes that you may encounter frequently.
To add an IOPS limit to a flavor, you will need the following:
- The
openstackcommand-line client - The
openrcfile containing appropriate credentials - The name of the flavor to change
- The value you would like to set the IOPS limit to.
- In our example, these values are as follows:
disk_read_iops= 100 IOPSdisk_write_iops= 100 IOPS
The following commands are used to add IOPS limits to a flavor:
- First, view the attributes of the flavor that is changing, noting that the
propertiesfield is blank:openstack flavor show openstack.cookbookThis gives an output like the following:
- Now we can add the IOPS limit with the following command:
openstack flavor set --property quota:disk_read_iops=100 --property quota:disk_write_iops=100 openstack.cookbook
- We can verify the IOPS limits by viewing the flavor properties:
openstack flavor show openstack.cookbookThis will bring back an output like the following, noting that we have now set the properties to reflect the IOPS imposed:
As with CPU limits, IO limits are defined at a flavor level. However, unlike CPU limits, IO limits can be applied by the hypervisor, the storage layer, or a combination of the two.
To set the IOPS limit values for a given flavor, the following openstack command is used:
openstack flavor set --property quota:disk_read_iops=[read_iops] --property quota:disk_write_iops=[write_iops] [name]
While both read and write IOPS are shown for completeness, you need not specify both.