To permanently remove nodes from the cluster, please proceed as follows:
Change the cluster configuration using dishostseditor:
Load the existing configuration.
In the cluster settings, change the topology to match the topology with all nodes removed.
Because the topology change might cut out nodes from the cluster at the "wrong" end, you have to make sure that the hostnames and the placement within the new topology for the remaining nodes is correct. To do this, change the hostnames of nodes by double-clicking their icon and changing the hostname in the displayed dialog box. If the SuperSockets configuration is based on the hostnames (not on the subnet addresses), make sure that the name of the socket interface matches a modified hostname.
Save the new cluster configuration. If desired, create and save or print the cabling instructions for the reduced cluster.
If you are not running dishostseditor on the frontend, transfer the saved files dishosts.conf and cluster.conf to the directory /etc/dis on the frontend.
Restart the network manager on the frontend. If you run sciadmin, the removed nodes should no longer show up. All other nodes should continue to stay green.
Uncable the nodes to be removed one by one, making sure that the remaining nodes are cabled according to the cabling instructions generated above.
On the nodes that have been removed from the cluster, the Dolphin Express software can easily be removed using the SIA option --wipe, like:
# sh DIS_install_<version>.sh --wipe
This will remove all Dolphin software packages, services and configuration data from the node.
If no SIA is available, the same effect can be achieved by manually uninstalling all packages that start with Dolphin-, remove potentially remaining installation directories (like /opt/DIS), and remove the configuration directory /etc/dis.
Perform the cable test from within sciadmin to ensure that the cabling is correct (see Chapter 4, Initial Installation, Section 3.7.4, “Cabling Correctness Test”).
Running the cable test will stop other traffic on the interconnect for the time the test is running, which can be up to a minute. If this is not an option, please use scidiag from the commandline to verify the functionality of the interconnect (see Chapter 7, Interconnect Maintenance, Section 1.1.3, “Static Interconnect Test”).