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Modify allocatable storage to ephemeral-storage #5490

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Sep 19, 2017
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Modify allocatable storage to ephemeral-storage #5490

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12 changes: 6 additions & 6 deletions docs/tasks/administer-cluster/reserve-compute-resources.md
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ on each node.

`Allocatable` on a Kubernetes node is defined as the amount of compute resources
that are available for pods. The scheduler does not over-subscribe
`Allocatable`. `CPU`, `memory` and `storage` are supported as of now.
`Allocatable`. `CPU`, `memory` and `ephemeral-storage` are supported as of now.

Node Allocatable is exposed as part of `v1.Node` object in the API and as part
of `kubectl describe node` in the CLI.
Expand Down Expand Up @@ -77,7 +77,7 @@ be configured to use the `systemd` cgroup driver.

### Kube Reserved

- **Kubelet Flag**: `--kube-reserved=[cpu=100m][,][memory=100Mi][,][storage=1Gi]`
- **Kubelet Flag**: `--kube-reserved=[cpu=100m][,][memory=100Mi][,][ephemeral-storage=1Gi]`
- **Kubelet Flag**: `--kube-reserved-cgroup=`

`kube-reserved` is meant to capture resource reservation for kubernetes system
Expand Down Expand Up @@ -107,7 +107,7 @@ exist. Kubelet will fail if an invalid cgroup is specified.

### System Reserved

- **Kubelet Flag**: `--system-reserved=[cpu=100mi][,][memory=100Mi][,][storage=1Gi]`
- **Kubelet Flag**: `--system-reserved=[cpu=100mi][,][memory=100Mi][,][ephemeral-storage=1Gi]`
- **Kubelet Flag**: `--system-reserved-cgroup=`


Expand Down Expand Up @@ -135,7 +135,7 @@ Memory pressure at the node level leads to System OOMs which affects the entire
node and all pods running on it. Nodes can go offline temporarily until memory
has been reclaimed. To avoid (or reduce the probability of) system OOMs kubelet
provides [`Out of Resource`](./out-of-resource.md) management. Evictions are
supported for `memory` and `storage` only. By reserving some memory via
supported for `memory` and `ephemeral-storage` only. By reserving some memory via
`--eviction-hard` flag, the `kubelet` attempts to `evict` pods whenever memory
availability on the node drops below the reserved value. Hypothetically, if
system daemons did not exist on a node, pods cannot use more than `capacity -
Expand Down Expand Up @@ -191,8 +191,8 @@ So expect a drop in `Allocatable` capacity in future releases.
Here is an example to illustrate Node Allocatable computation:

* Node has `32Gi` of `memory`, `16 CPUs` and `100Gi` of `Storage`
* `--kube-reserved` is set to `cpu=1,memory=2Gi,storage=1Gi`
* `--system-reserved` is set to `cpu=500m,memory=1Gi,storage=1Gi`
* `--kube-reserved` is set to `cpu=1,memory=2Gi,ephemeral-storage=1Gi`
* `--system-reserved` is set to `cpu=500m,memory=1Gi,ephemeral-storage=1Gi`
* `--eviction-hard` is set to `memory.available<500Mi,nodefs.available<10%`

Under this scenario, `Allocatable` will be `14.5 CPUs`, `28.5Gi` of memory and
Expand Down