Node Tuning Operator - low-level tunning in OpenShift (4.16)
What do you use the Node Tuning Operator for?
For low-level hardening of OpenShift nodes
(virtual memory, network buffers, hugepages, disk schedulers..)
Does the Node Tuning Operator need to be installed?
No
It is a Cluster Operator (installed by OpenShift by default).
What does the Node Tuning Operator manage?
The system daemon tuned at the node level (OS level).
How is the Node Tuning Operator deployed in the cluster?
As a daemonset - it runs on every node.
Which system elements can be modified using tuned? (3 examples)
- sysctl settings
- vm (e.g., transparent_hugepages)
- disk (e.g., scheduler)
What is the name of the CRD used by the Node Tuning Operator?
Tuned
What is the name of the default CR with the TuneD profile?
Tuned/default
Can the content of the default profile (Tuned/default) be modified?
No - it is managed by the operator
(any changes you make may be overwritten)
What should you do to apply custom tuning to nodes?
Create custom Tuned CR resources.
Which labels should be used to correlate a Tuned profile with a specific node?
Recommended: Node labels
Where can I find example profiles?
https://github.com/openshift/cluster-node-tuning-operator/tree/master/examples
How can I list available tuned profiles?
By using the pod:
oc exec tuned-h8lcf -n openshift-cluster-node-tuning-operator -- find /usr/lib/tuned/ -name tuned.conf -printf '%h\n' | sed 's|^.*/||'
(The command displays the names of directories containing the tuned.conf)
How can I view the content of tuned profiles?
By using the pod:
oc exec tuned-h8lcf -n openshift-cluster-node-tuning-operator -- find /usr/lib/tuned/openshift{,-control-plane,-node} -name tuned.conf -exec grep -H ^ {} \;
(The command displays the contents of all tuned.conf)
Are there default tuned profiles for OpenShift?
Yes - they come with the tuned package (CoreOS)
(profiles: openshift-control-plane and openshift-node).
How can you check which profiles are active on your nodes?
CR: profile in openshift-cluster-node-tuning-operator namespace
oc get profile.tuned.openshift.io -n openshift-cluster-node-tuning-operator
If the active profile on a node has a "Degraded" status, where should you look for more information?
In the status of the cluster operator node-tuning
oc get co/node-tuning -n openshift-cluster-node-tuning-operator
How many profiles can run simultaneously on a specific node?
One
What sections does the Tuned CR have?
- profile
- recommend
- managementState
What modes can the Tuned Operator have?
- Managed (default)
- Unmanaged
- Removed
What does the Managed mode of the Tuned Operator do?
Monitors and applies changes related to profiles.
What does the Unmanaged mode of the Tuned Operator do?
Pause mode (ignores configuration changes).
What does the Removed mode of the Tuned Operator do?
Deletes all resources it has created.
Where can the mode of the Tuned Operator be changed?
The spec.managementState field in the CR: Tuned/default
oc edit tuned/default
What does the profile section in the Tuned CR contain? (2)
- profile name
- profile content
What does the recommend section in the Tuned CR contain?
Logic for selecting profiles for specific nodes
(Correlates profiles with nodes)
Can multiple Tuned CR specifications be defined?
Yes - they are merged (both: all defined profiles and all node correlations)
Can profiles be easily defined depending on the cloud provider?
Yes - The documentation explains how to use spec.providerID to activate specific profiles depending on the cloud provider
Can node tuning be used for hosted cluster nodes?
Yes - more info in documentation:
Where is the official documentation for the Tuned Node Operator?
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