This is documentation for MapR Version 5.0. You can also refer to MapR documentation for the latest release.

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In a large cluster (100 nodes or more) create CLDB-only nodes to ensure high performance. This configuration also provides additional control over the placement of the CLDB data, for load balancing, fault tolerance, or high availability (HA). Setting up CLDB-only nodes involves restricting the CLDB volume to its own topology and making sure all other volumes are on a separate topology. Because both the CLDB-only path and the non-CLDB path are children of the root topology path, new non-CLDB volumes are not guaranteed to keep off the CLDB-only nodes. To avoid this problem, set a default volume topology. See Setting Default Volume Topology.

To set up a CLDB-only node:

  1. SET UP the node as usual:
    • PREPARE the node, making sure it meets the requirements.
    • ADD the MapR Repository.
  2. INSTALL the following packages to the node.
    • mapr-cldb
    • mapr-webserver
    • mapr-core
    • mapr-fileserver

To set up a volume topology that restricts the CLDB volume to specific nodes:

  1. Move all CLDB nodes to a CLDB-only topology (e. g. /cldbonly) using the MapR Control System or the following command:
    maprcli node move -serverids <CLDB nodes> -topology /cldbonly
  2. Restrict the CLDB volume to the CLDB-only topology. Use the MapR Control System or the following command:
    maprcli volume move -name mapr.cldb.internal -topology /cldbonly
  3. If the CLDB volume is present on nodes not in /cldbonly, increase the replication factor of mapr.cldb.internal to create enough copies in /cldbonly using the MapR Control System or the following command:
    maprcli volume modify -name mapr.cldb.internal -replication <replication factor>
  4. Once the volume has sufficient copies, remove the extra replicas by reducing the replication factor to the desired value using the MapR Control System or the command used in the previous step.

To move all other volumes to a topology separate from the CLDB-only nodes:

  1. Move all non-CLDB nodes to a non-CLDB topology (e. g. /defaultRack) using the MapR Control System or the following command:
    maprcli node move -serverids <all non-CLDB nodes> -topology /defaultRack
  2. Restrict all existing volumes to the topology /defaultRack using the MapR Control System or the following command:
    maprcli volume move -name <volume> -topology /defaultRack
    All volumes except mapr.cluster.root are re-replicated to the changed topology automatically.

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    To prevent subsequently created volumes from encroaching on the CLDB-only nodes, set a default topology that excludes the CLDB-only topology.

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