JS7 JobScheduler

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Table of Contents

Introduction

  • The Controller The JS7 - Cluster Architecture brings high-availability including fail-over capabilities for the deployment of scheduling objects and for execution of workflows.
    • Two Controller instances are operated on different servers to synchronize JS7 - Order State Transitions and log events.
    • Automated fail-over guarantees high-availability and restart capability of a Controller Cluster (active-passive cluster).
  • Use of the Controller Cluster is subject to the agreements of the JS7 - License.

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The architecture applies to the clustering of two Controller instances acting as a an active-passive cluster:

  • Controller instances synchronize order state information and perform fail-over (automated) and switch-over (by user intervention).
  • There is no need for use of an active cluster that aims at scalability: a single Controller instance offers unlimited scalability.

There are situations when cluster members need an arbitrator a witness to decide which member should take the active role:

  • If both Controller instances are shutdown and are restarted then the previously active instance cannot know if in between the standby instance was active. It is pointless to rely on operating system timestamps to clarify this situation.
  • If a Controller instance continues to run but is isolated in the network in a way that no network connection can be established by the partner instance then this situation requires an arbitratora witness.

The role of the arbitrator witness is to act as a Cluster Watch and to add a vote in situations for which Controller instances cannot decide about the active role.

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The Cluster Watch role is available from JOC Cockpit and alternatively in earlier releases from an Agent:

  • It is generally recommended to use JOC Cockpit as Cluster Watch as this provides high availability and fail-over of the Cluster Watch role if a JOC Cockpit Cluster is used.
  • In a scenario when a number of Controller instances are managed by JOC Cockpit users might tend to use individual Agents acting as Cluster Watch per Controller.

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Any number of JOC Cockpit instances can act as be operated. The active JOC Cockpit instance acts as a Cluster Watch to determine the active Controller instance.

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Further Resources

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