Administrators use disable Service Engine (SE) functionality to stop placement of virtual services on certain SEs and (optionally) to migrate multiple virtual services (VSs) from an existing SE. This can be useful during maintenance or decommissioning of an SE. Currently, VS migration lets user migrate a VS from one SE to another SE. Underneath, disable relies on VS migration from the disabled SE to prevent outages and performance degradation.
One can disable an SE using the Avi UI, CLI, or REST API.
The SE object
enable_state reflects the three states of an SE. They are SE_STATE_ENABLED, SE_STATE_DISABLED_FOR_PLACEMENT, and SE_STATE_DISABLED:
- SE_STATE_ENABLED: Default state of an SE
- SE_STATE_DISABLED_FOR_PLACEMENT: In this state the SE continues to serve traffic for VSs already placed on it. However, new VSs will not be placed on it. Migration of a VS can not be initiated in this state.
- SE_STATE_DISABLED: New VS placements onto the SE are disallowed. In addition, the SE starts migrating its virtual services to others in its SE group. Client load is redirected in the same way native SE scaling is implemented.
It is important to note that (re)placements are made on the SE group in the usual way, and depends upon parameters set for the SE group and prevailing load conditions. Consequently, migration does not necessarily imply to a newly-created SE.
The following events are generated to reflect the status of this migration: * MIGRATE_SE_STARTED: This event is generated when system initiates migration of VSs on the disabled SE. The SE enters the OPER_DISABLING state. * MIGRATE_SE_RESTARTED: If there is an error encountered while migrating, the system attempts to reinitiate migration. * MIGRATE_SE_FINISHED: This event indicates all virtual services have been successfully migrated to other SEs without any failures and that the SE is not serving any virtual services. The SE enters the OPER_DISABLED state. * MIGRATE_SE_FAILED: This state indicates system failed to migrate at least one VS. The VSs which encounter failures during migration continue to serve traffic. Manual intervention is required to completely take remaining VSs out of that SE. SE goes to OPER_ERROR_DISABLED state.
- An SE remains in the SE_STATE_DISABLED state after the migration process is completed. Disabled SEs remain connected to the Controller and are counted towards the limit on the number of SEs in the SE group.
- The decommissioning of an SE requires an SE delete operation.