Add local ephemeral storage alpha feature in managing compute resource (

#5522)

* Add local ephemeral storage alpha feature in managing compute resource

Since 1.8, we add the local ephemeral storage alpha feature as one
resource type to manage. Add this feature into the doc.

* Update manage-compute-resources-container.md

* Update manage-compute-resources-container.md

* Update manage-compute-resources-container.md

* Update manage-compute-resources-container.md

* Update manage-compute-resources-container.md

* Update manage-compute-resources-container.md

docs/concepts/configuration/manage-compute-resources-container.md

@@ -303,7 +303,65 @@ LastState: map[terminated:map[exitCode:137 reason:OOM Killed startedAt:2015-07-0
 You can see that the Container was terminated because of `reason:OOM Killed`,
 where `OOM` stands for Out Of Memory.
 
-## Opaque integer resources (Alpha feature)
+## Local ephemeral storage (alpha feature)
+
+Kubernetes version 1.8 introduces a new resource, _ephemeral-storage_ for managing local ephemeral storage. In each Kubernetes node, kubelet's root directory (/var/lib/kubelet by default) and log directory (/var/log) are stored on the root partition of the node. This partition is also shared and consumed by pods via EmptyDir volumes, container logs, image layers and container writable layers.
+
+This partition is “ephemeral” and applications cannot expect any performance SLAs (Disk IOPS for example) from this partition. Local ephemeral storage management only applies for the root partition; the optional partition for image layer and writable layer is out of scope.
+
+**Note:** If an optional runntime partition is used, root parition will not hold any image layer or writable layers. 
+{: .note}
+
+### Requests and limits setting for local ephemeral storage
+Each Container of a Pod can specify one or more of the following:
+
+* `spec.containers[].resources.limits.ephemeral-storage`
+* `spec.containers[].resources.requests.ephemeral-storage`
+
+Limits and requests for `ephemeral-storage` are measured in bytes. You can express storage as
+a plain integer or as a fixed-point integer using one of these suffixes:
+E, P, T, G, M, K. You can also use the power-of-two equivalents: Ei, Pi, Ti, Gi,
+Mi, Ki. For example, the following represent roughly the same value:
+
+```shell
+128974848, 129e6, 129M, 123Mi
+```
+
+For example, the following Pod has two Containers. Each Container has a request of 2GiB of local ephemeral storage. Each Container has a limit of 4GiB of local ephemeral storage. Therefore, the Pod has a request of 4GiB of local ephemeral storage, and a limit of 8GiB of storage.
+
+```yaml
+apiVersion: v1
+kind: Pod
+metadata:
+  name: frontend
+spec:
+  containers:
+  - name: db
+    image: mysql
+    resources:
+      requests:
+        ephemeral-storage: "2Gi"
+      limits:
+        ephemeral-storage: "4Gi"
+  - name: wp
+    image: wordpress
+    resources:
+      requests:
+        ephemeral-storage: "2Gi"
+      limits:
+        ephemeral-storage: "4Gi"
+```
+
+### How Pods with ephemeral-storage requests are scheduled
+
+When you create a Pod, the Kubernetes scheduler selects a node for the Pod to 
+run on. Each node has a maximum amount of local ephemeral storage it can provide for Pods. (For more information, see ["Node Allocatable"](/docs/tasks/administer-cluster/reserve-compute-resources/#node-allocatable) The scheduler ensures that the sum of the resource requests of the scheduled Containers is less than the capacity of the node.
+
+### How Pods with ephemeral-storage limits run
+
+For container-level isolation, if a Container's writable layer and logs usage exceeds its storage limit, the pod will be evicted. For pod-level isolation, if the sum of the local ephemeral storage usage from all containers and also the pod's EmptyDir volumes exceeds the limit, the pod will be evicted.
+
+## Opaque integer resources (alpha feature)
 
 {% include feature-state-deprecated.md %}