Configuring high availability in Teracloud® Streams instances

If you configure high availability for the management services in an instance, Teracloud® Streams can switch to using standby services in the event of a software, hardware, or network interruption.

Before you begin

For high availability with automatic recovery from failures, the domain controller service must be running as a Linux™ system service on the Teracloud® Streams resource. For more information, see Options for setting up the domain controller service on Teracloud® Streams resources.

About this task

To configure high availability for an instance, set the instance.highAvailabilityCount instance property to a value greater than one. This property specifies the total number of each Teracloud® Streams instance management service. For example, a value of three means that there is one active and two standby services for each management service in the instance.

Teracloud® Streams can switch to the standby services in the event of a software, hardware, or network interruption.

A standby service is not created for the application deployment service on each application resource, however, the application deployment service is restarted in the event of a software, hardware, or network interruption. There can only be one application service for each resource, even if the instance.highAvailabilityCount is set to a higher value. For more information about this instance property, run streamtool man properties.

To affect the placement of active and standby services on the resources that are allocated to your instance, tag the resources. For example, application services run on resources with the application tag, management services run on resources with management tag, and view services run on resources with the view tag. For more information about the Teracloud® Streams services and tags, see Domain and instance services.

Note: There can be only one data service for each resource. The standby services for the data service can run on other resources that are tagged as data or management resources.

Procedure

  • To change the instance.highAvailabilityCount instance property value, use the Streams Console or the streamtool setproperty command.
    You can also specify that property value when you create the instance.
  • To change the tags that are associated with resources, use the Streams Console or the streamtool chhost command.
    For more information, see Assigning tags to resources in a domain.