Adding or removing nodes in a system


This section refers to Kognitio Standalone only

Adding Nodes to a System

The normal procedure for adding nodes to a Kognitio system is as follows:

  1. Make a copy of the old configuration file in a safe place (copy from /opt/kognitio/wx2/etc/config to another location), and make a note of the current pointer by running ls -ltr /opt/kognitio/wx2/current.

  2. Physically install the new nodes into the existing environment - this may include joining the node with existing racks, connecting network cables and so on.

  3. Ensure the new nodes are setup identically to existing nodes, with the same hardware specs, same OS, same Kognitio software version, the same config file etc. If disk resources on the new nodes will be used for Kognitio, ensure they are identical as well. Ideally the OS and software should be deployed with the server vendor’s deployment tool, applying an image of existing nodes onto new nodes. If in a cloud environment where the IP addresses of all nodes need to be specified in the config file, ensure this is done for the config file on all nodes.

  4. Start the new nodes.

  5. Use wxprobe -HNF to confirm that the new nodes are identical to the existing ones. Also, ensure that all drivers and firmware are identical (e.g. use ethtool -i eth2 to check drivers/firmware for eth2, and similarly for other interfaces).

  6. Double-check that the current pointer on every node is as expected - i.e. the same as at step 1. You can verify this with wxtool -S 'ls -ltr /opt/kognitio/wx2'.

  7. Use wxviconf to ensure the config file is as in step 1 (subject to any modifications for a cloud environment as mentioned in step 3). The new smds will attempt to synchronise items such as the current pointer and config file to the latest version (determined by timestamp), so we want to ensure that nothing has gone awry here.

  8. Restart the Kognitio software. Kognitio will auto-identify all new nodes and configure them into the system. Extra processor and memory resource will be immediately available, disk resource will be visible but not used at this time.

  9. Consider running a shape test on the new system to ensure no problems have been introduced by adding the nodes.

  10. If you want to use disk resources on the new nodes, then a reconfigure process can then be started at a convenient time to make the new disk capacity available to the system and to re-distribute the existing data.

Removing nodes from a system

To remove nodes from a system, see Removing disks and/or nodes from a system.