Changing required node settings

Node settings for services

The following table shows the services that require changes to specific node settings, with links to instructions for changing the settings:

Load balancer timeout settings

To prevent connections from being closed before processes complete, you might need to adjust the timeout settings on your load balancer node.

This setting is also recommended if you are working with large data sets or you have slower network speeds. For example, you might need to increase this value if you receive a timeout or failure when you upload a large file.

The following procedures show how to change the timeout settings if you are using HAProxy. If you are using a load balancer other than HAProxy, see the documentation for your load balancer for information about how to configure the timeout settings.

If you are using HAProxy, the load balancer node is the OpenShift cluster public node.

CRI-O container settings

To ensure that services can run correctly, you must adjust values in the CRI-O container settings to specify the maximum number of processes and the maximum number of open descriptor files.

These settings are required for the CRI-O CRI-O container runtime on the OpenShift Container Platform.

To change CRI-O settings, you modify the contents of the crio.conf file and pass those updates to your nodes as a machine config.

1. Obtain a copy of the existing crio.conf file from a worker node. For example, run the following command, replacing $node with one of the worker nodes. You can obtain the worker nodes by using the oc get nodes command.

   scp core@$node:/etc/crio/crio.conf /tmp/crio.conf

   If the crio.conf file doesn't exist in the path /etc/crio/crio.conf, use the path /etc/crio/crio.conf.d/00-default instead.

   If you don't have access by using the scp command, ask your cluster administrator for the crio.conf file.

   Make sure that you obtain the latest version of the crio.conf file.

2. In the crio.conf file, make the following changes in the [crio.runtime] section (uncomment the lines if necessary):
   • To set the maximum number of open files, change the default_ulimits setting to at least 66560, as follows.
     Note: When you set the default_ulimits parameter in the crio.conf file, make sure that the ulimit -n settings in the /etc/security/limits.conf files on the worker machines also are set to at least 66560.

     ……
     [crio.runtime]
     default_ulimits = [
             "nofile=66560:66560"
     ]
     ……

   • To set the maximum number of processes, change the pids_limit setting to at least 12288, as follows.

     ……
     # Maximum number of processes allowed in a container.
     pids_limit = 12288
     ……
     

3. Create a machineconfig object YAML file, as follows, and apply it.
   Note: If you are using Cloud Pak for Data on OpenShift Container Platform version 4.6, the ignition version is 3.1.0. If you are using Cloud Pak for Data on OpenShift Container Platform version 4.8, change the ignition version to 3.2.0.

   Note: On Mac OS systems, remove -w0 at the end of the source value so that you do not receive an error when you apply the machineconfig object YAML file.

   cat << EOF | oc apply -f -
   apiVersion: machineconfiguration.openshift.io/v1
   kind: MachineConfig
   metadata:
     labels:
       machineconfiguration.openshift.io/role: worker
     name: 99-worker-cp4d-crio-conf
   spec:
     config:
       ignition:
         version: 3.1.0
       storage:
         files:
         - contents:
             source: data:text/plain;charset=utf-8;base64,$(cat /tmp/crio.conf | base64 -w0)        
           mode: 0644
           overwrite: true
           path: /etc/crio/crio.conf
   EOF
   

4. Monitor all of the nodes to ensure that the changes are applied, by using the following command:

   watch oc get nodes

   You can also use the following command to confirm that the MachineConfig sync is complete:

   watch oc get mcp

Kernel parameter settings

Power settings

1. Label all small core KVM capable worker nodes that are not running Db2 Warehouse workloads to SMT=2. For example:

   oc label node <node> SMT=2 --overwrite

2. Label all small core KVM capable worker nodes that are running Db2 Warehouse workloads to SMT=4. For example:

   oc label node <node> SMT=4 --overwrite

3. Label all big core PowerVM capable worker nodes that are not running Db2 Warehouse workloads to SMT=4. For example:

   oc label node <node> SMT=4 --overwrite

4. Label all big core PowerVM capable worker nodes that are running Db2 Warehouse workloads to SMT=8. For example:

   oc label node <node> SMT=8 --overwrite 

5. Create a YAML file, smt.yaml, with the following content:

   apiVersion: machineconfiguration.openshift.io/v1
   kind: MachineConfig
   metadata:
     labels:
       machineconfiguration.openshift.io/role: worker
     name: 99-worker-smt
   spec:
     kernelArguments:
     - slub_max_order=0
     config:
       ignition:
         version: 3.1.0
       storage:
         files:
         - contents:
             source: data:text/plain;charset=utf-8;base64,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
             verification: {}
           filesystem: root
           mode: 0755
           overwrite: true
           path: /usr/local/bin/powersmt
       systemd:
         units:
           - name: smt.service
             enabled: true
             contents: |
               [Unit]
               Description=Set SMT
               After=network-online.target
               Before= crio.service
               [Service]
               Type=oneshot
               RemainAfterExit=yes
               ExecStart=/usr/local/bin/powersmt
               [Install]
               WantedBy=multi-user.target
   

6. Run the oc create command to apply the changes.

   Note: You must ensure that the cluster master nodes (or control plane) are in Ready status before you issue this command.

   oc create -f smt.yaml

   Your worker nodes will perform a rolling reboot action to update the kernel argument slub_max_order and set the labeled SMT level.

   Note:

   • All the worker nodes are rebooted after the command is issued. The slub_max_order=0 kernel argument and the specified SMT level are applied to all the worker nodes after the reboot completes. The SMT level on the worker nodes that are not labeled will be set to the default value.
   • After this process is done, if the SMT level on a particular worker node needs to be changed, you must label that worker node with the desired SMT level and manually reboot it.