Scaling the Cherwell Service Host

Cherwell® Service Management (CSM) uses a dedicated message queue system to allow horizontal and vertical scaling for one or more server components. Scaling CSM enables the system to use a network of machines to distribute work, providing more resources to alleviate barriers and improve availability.

Common Terms and Definitions

See the following common terms and definitions that are related to horizontal and vertical scaling deployments.

  • Horizontal Scale — The process of adding more machines to a pool of resources.
  • Vertical Scale — The process of adding more resources (CPU, RAM) to a single machine.
  • Queue — The message destination and repository where messages are stored until they are delivered to a CSM Service.
  • Scaled Services — Services include Automation Process Service, Email and Event Monitor Service, Mail Delivery Services, and Scheduling Service.
  • Enqueue — To add a unit of work or data to the queue to await processing.
  • Dequeue — To remove a unit of work or data from the queue to begin processing.

Configuration Rules and Considerations

The number of configurations for CSM is widely varied, but these constant rules must be followed for a successful configuration.

  • At least one of each of the scaled services must be enabled.
  • If a scheduled group item makes use of a resource that only exists on a single node, then the system must be configured to only run scheduled group items of that group on that specific node.
  • Cherwell Service Host comes preconfigured to vertically scale all services equally. This configuration may not work in all installations and can be adjusted, allowing the services to scale vertically to different levels.
  • To ensure the correct actions are taken, consider the current utilization of a node before changing the scale of that node,