Lowering K‑Safety to Enable Node Removal

A database with a K-safety level of 1 requires at least three nodes to operate, and a database with a K-safety level 2 requires at least 5 nodes to operate. You can check the cluster's current K-safety level as follows:

=> SELECT current_fault_tolerance FROM system;
 current_fault_tolerance
-------------------------
                       1
(1 row)

To remove a node from a cluster with the minimum number of nodes that it requires for K-safety, first lower the K-safety level with MARK_DESIGN_KSAFE.

Lowering the K-safety level of a database to 0 eliminates Vertica's fault tolerance features. If you must reduce K-safety to 0, first back up the database.

  1. Connect to the database with Administration Tools or vsql.

  2. Call the function MARK_DESIGN_KSAFE:

    SELECT MARK_DESIGN_KSAFE(n);

    where n is the new K-safety level for the database.