Managing decision management nodes

Manage the decision management nodes in your application by running certain actions for them, for example, repair or clean-up.

Note: This procedure applies only to on-premises environments.
  1. In the header of Dev Studio, click Configure > Decisioning > Infrastructure > Services.
  2. Select the decision management service for which you want to run a selected action by clicking the corresponding tab.
  3. In the row for a selected DM node, click Execute.
  4. On the Execute menu, select one of the available actions:
    Option Description
    Start Activates the DM node. The status of the node changes to NORMAL.
    Stop Deactivates the DM node. The status of the node changes to STOPPED.
    Repair Removes inconsistencies across all replicas of the data sets in a DM node.
    Run this operation in the following cases:
    • As part of node recovery, when bringing a node back into the cluster after a failure.
    • As part of node maintenance, when the node contains data that is not frequently read.
    • As part of the node update process, when the node was offline.
    Compact Invokes the process in which the Cassandra database combines multiple physical data files on the file system to improve the performance of partition scans and to reclaim space from deleted data. Compaction is a background operation that runs on a regular basis across all nodes in the DM node cluster; however, you can run it explicitly on one DM node by selecting the Compact action.
    CAUTION:
    The compaction operation causes a temporary spike in disk usage and disk I/O. Do not run this operation during peak usage hours on multiple DM nodes concurrently, because it affects performance for any process or request accessing the DM node storage.
    Clean up Removes keys that no longer belong to the DM node. Keys do not belong to a DM node if data was decommissioned, or if the node was rebalanced within the DM node cluster.
    CAUTION:
    The clean up operation causes a temporary spike in disk usage and disk I/O. Do not run this operation during peak usage hours on multiple DM nodes concurrently, because it affects performance for any process or request accessing the DM node storage
    Decommission Removes the node from the DM node cluster. The data contained in the DM node storage is transferred to other nodes in the DM node cluster.
    Note: If you decommission a Data Flow service node that has active data flow runs, the status of that node changes to LEAVING, and the node is not decommissioned until all active data flow runs are finished.