Ceilometer’s native database capabilities is intended for post processing and auditing purposes where responsiveness is not a requirement. It captures the full fidelity of each datapoint and thus is not designed for low latency use cases. For more responsive use cases, it’s recommended to store data in an alternative source such as Gnocchi. Please see Moving from Ceilometer to Gnocchi to find more information.
As of Liberty, alarming support, and subsequently its database, is handled by Aodh.
Selecting a database backend for Ceilometer should not be done lightly for numerous reasons:
The following is a table indicating the status of each database drivers:
|Driver||API querying||API statistics|
|HBase||Yes||Yes, except groupby & selectable aggregates|
There currently exists no migration tool between the services. To transition to Gnocchi, multiple dispatchers can be enabled in the Collector to capture data in both the native Ceilometer database and Gnocchi. This will allow you to test Gnocchi and transition to it fully when comfortable. The following should be included in addition to the required configurations for each backend:
[DEFAULT] meter_dispatchers=database meter_dispatchers=gnocchi event_dispatchers=gnocchi
In somes cases, it is possible to disable keystone authentication for Gnocchi to remove the overhead of token creation/verification when request authentication doesn’t matter. This will increase the performance of Gnocchi.
Example of configuration:
[dispatcher_gnocchi] auth_section=service_credentials_gnocchi [service_credentials_gnocchi] auth_type=gnocchi-noauth roles = admin user_id = <ceilometer_user_id> project_id = <ceilometer_project_id> endpoint = <gnocchi_endpoint>