Project deployment options determine how your project is deployed in a cluster and how it functions at runtime. These parameters, including project options, active-active instances, failover intervals, and project deployment type options, are set in the CCR file manually or within Studio.
Active-active deployments are available only when you define the project as an ha-project in the CCR file. An active-active deployment means that two instances of a project run simultaneously in a cluster. The two instances of the project are started by the cluster manager on two different hosts.
One instance of the project is elected as primary instance. If one of the instances is already active, it is the primary instance. If the failed instance restarts, it assumes the secondary position and maintains this position unless the current instance fails or is stopped.
The number of instances available depends on the deployment type chosen by the user, either high availability (HA) or Non-HA. When a project is configured in HA (active-active) mode, two instances are created: primary and secondary. You can set affinity and cold failover options for each instance, including failover intervals and failure per interval options.
A project fails when it does not run properly or stops running properly. A failover occurs when a failed project or server switches to another server to continue processing. Failovers may result in a project restart, if defined. Restarts can be limited based on definition of failure intervals and restarts per interval. Failover options, accessed using an instance configuration, include:
| Field | Description |
|---|---|
| Failover | Either enabled or disabled. When disabled, project failover restarts are not permitted. When enabled, failure interval and failures per interval fields can be accessed and restarts are permitted. |
| Failures per interval | Specifies the number of restarts the project can attempt within a given interval. This count can be reset to zero by a manual start of the project or if failures are dropped from the list because they are older than the size of the interval. |
| Failure interval | (Optional) This specifies the time, in seconds, that make up an interval. If left blank, the interval time is infinite. |
| Field | Description |
|---|---|
| Name | Enter the name of the object of the affinity, that is, the controller name or instance name that the affinity is set for. For instance affinities, the affinity for one instance should refer to the second instance. |
| Strength | Strong or weak. Strong requires the project to run on a specific controller, and no others. If weak, the project preferentially starts on the defined controller, but if that controller is unavailable, it may start on another available controller. |
| Charge | Positive or negative. If positive, the project runs on the controller. If negative, the project does not run on the controller. |