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66 lines
1.7 KiB
Plaintext
66 lines
1.7 KiB
Plaintext
// Module included in the following assemblies:
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//
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// * nodes/nodes-cluster-overcommit.adoc
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// * post_installation_configuration/node-tasks.adoc
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:_mod-docs-content-type: CONCEPT
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[id="nodes-cluster-overcommit-configure-nodes_{context}"]
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= Understanding nodes overcommitment
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In an overcommitted environment, it is important to properly configure your node to provide best system behavior.
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When the node starts, it ensures that the kernel tunable flags for memory
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management are set properly. The kernel should never fail memory allocations
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unless it runs out of physical memory.
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To ensure this behavior, {product-title} configures the kernel to always overcommit
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memory by setting the `vm.overcommit_memory` parameter to `1`, overriding the
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default operating system setting.
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{product-title} also configures the kernel not to panic when it runs out of memory
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by setting the `vm.panic_on_oom` parameter to `0`. A setting of 0 instructs the
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kernel to call oom_killer in an Out of Memory (OOM) condition, which kills
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processes based on priority.
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You can view the current setting by running the following commands on your nodes:
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[source,terminal]
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----
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$ sysctl -a |grep commit
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----
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.Example output
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[source,terminal]
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----
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#...
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vm.overcommit_memory = 0
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#...
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----
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[source,terminal]
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----
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$ sysctl -a |grep panic
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----
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.Example output
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[source,terminal]
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----
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#...
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vm.panic_on_oom = 0
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#...
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----
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[NOTE]
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====
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The above flags should already be set on nodes, and no further action is
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required.
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====
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You can also perform the following configurations for each node:
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* Disable or enforce CPU limits using CPU CFS quotas
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* Reserve resources for system processes
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* Reserve memory across quality of service tiers
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