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22 lines
1.9 KiB
Plaintext
22 lines
1.9 KiB
Plaintext
// Module included in the following assemblies:
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//
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// * rosa_cluster_admin/rosa-configuring-pid-limits.adoc
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:_mod-docs-content-type: CONCEPT
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[id="understanding-process-id-limits_{context}"]
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= Understanding process ID limits
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In {product-title}, consider these two supported limits for process ID (PID) usage before you schedule work on your cluster:
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* Maximum number of PIDs per pod.
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+
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The default value is 4,096 in {product-title} 4.11 and later. This value is controlled by the `podPidsLimit` parameter set on the node.
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* Maximum number of PIDs per node.
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The default value depends on link:https://access.redhat.com/documentation/en-us/openshift_container_platform/4.15/html-single/nodes/index#nodes-nodes-resources-configuring[node resources]. In {product-title}, this value is controlled by the link:https://kubernetes.io/docs/tasks/administer-cluster/reserve-compute-resources/#system-reserved[`--system-reserved`] parameter, which reserves PIDs on each node based on the total resources of the node.
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When a pod exceeds the allowed maximum number of PIDs per pod, the pod might stop functioning correctly and might be evicted from the node. See link:https://kubernetes.io/docs/concepts/scheduling-eviction/node-pressure-eviction/#eviction-signals-and-thresholds[the Kubernetes documentation for eviction signals and thresholds] for more information.
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When a node exceeds the allowed maximum number of PIDs per node, the node can become unstable because new processes cannot have PIDs assigned. If existing processes cannot complete without creating additional processes, the entire node can become unusable and require reboot. This situation can result in data loss, depending on the processes and applications being run. Customer administrators and Red Hat Site Reliability Engineering are notified when this threshold is reached, and a `Worker node is experiencing PIDPressure` warning will appear in the cluster logs.
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