OSDOCS-16945# CQA work Storage - understanding ephemeral storage

Author: Lisa Pettyjohn

modules/storage-ephemeral-storage-manage.adoc

@@ -8,6 +8,7 @@
 [id=storage-ephemeral-storage-manage_{context}]
 = Ephemeral storage management
 
+[role="_abstract"]
 Cluster administrators can manage ephemeral storage within a project by setting quotas that define the limit ranges and number of requests for ephemeral storage across all pods in a non-terminal state. Developers can also set requests and limits on this compute resource at the pod and container level.
 
 You can manage local ephemeral storage by specifying requests and limits. Each container in a pod can specify the following:
@@ -16,7 +17,7 @@ You can manage local ephemeral storage by specifying requests and limits. Each c
 * `spec.containers[].resources.requests.ephemeral-storage`
 
 [id=storage-ephemeral-storage-limits-requests-units_{context}]
-== Ephemeral storage limits and requests units
+.Ephemeral storage limits and requests units
 Limits and requests for ephemeral storage are measured in byte quantities. You can express storage as a plain integer or as a fixed-point number 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 quantities all represent approximately the same value: 128974848, 129e6, 129M, and 123Mi.
@@ -27,7 +28,7 @@ The suffixes for each byte quantity are case-sensitive. Be sure to use the corre
 ====
 
 [id=storage-ephemeral-storage-requests-limits_{context}]
-== Ephemeral storage requests and limits example
+.Ephemeral storage requests and limits example
 The following example configuration file shows a pod with two containers:
 
 * Each container requests 2GiB of local ephemeral storage.
@@ -49,9 +50,9 @@ spec:
     image: images.my-company.example/app:v4
     resources:
       requests:
-        ephemeral-storage: "2Gi" <1>
+        ephemeral-storage: "2Gi"
       limits:
-        ephemeral-storage: "4Gi" <2>
+        ephemeral-storage: "4Gi"
     volumeMounts:
     - name: ephemeral
       mountPath: "/tmp"
@@ -69,12 +70,12 @@ spec:
     - name: ephemeral
       emptyDir: {}
 ----
-<1> Container request for local ephemeral storage.
-<2> Container limit for local ephemeral storage.
+* `spec.containers.name.resources.requests.ephemeral-storage`: Container request for local ephemeral storage.
+* `spec.containers.name.resources.limits.ephemeral-storage`: Container limit for local ephemeral storage.
 
 ifndef::microshift[]
 [id=storage-ephemeral-storage-scheduling-eviction_{context}]
-== Ephemeral storage configuration effects pod scheduling and eviction
+.Ephemeral storage configuration effects pod scheduling and eviction
 The settings in the pod spec affect both how the scheduler makes a decision about scheduling pods and when kubelet evicts pods.
 
 * First, the scheduler ensures that the sum of the resource requests of the scheduled containers is less than the capacity of the node. In this case, the pod can be assigned to a node only if the node's available ephemeral storage (allocatable resource) is more than 4GiB.
@@ -84,7 +85,7 @@ endif::microshift[]
 
 ifdef::microshift[]
 [id=storage-ephemeral-storage-eviction_{context}]
-== Ephemeral storage configuration effects pod eviction
+.Ephemeral storage configuration effects pod eviction
 The settings in the pod spec affect when kubelet evicts pods. At the container level, because the first container sets a resource limit, kubelet eviction manager measures the disk usage of this container and evicts the pod if the storage usage of the container exceeds its limit (4GiB). The kubelet eviction manager also marks the pod for eviction if the total usage exceeds the overall pod storage limit (8GiB).
 
 [NOTE]

modules/storage-ephemeral-storage-monitoring.adoc

@@ -7,11 +7,12 @@
 [id=storage-ephemeral-storage-monitoring_{context}]
 = Monitoring ephemeral storage
 
+[role="_abstract"]
 You can use `/bin/df` as a tool to monitor ephemeral storage usage on the volume where ephemeral container data is located, which is `/var/lib/kubelet` and `/var/lib/containers`. The available space for only `/var/lib/kubelet` is shown when you use the `df` command if `/var/lib/containers` is placed on a separate disk by the cluster administrator.
 
 .Procedure
 
-* To show the human-readable values of used and available space in `/var/lib`, enter the following command:
+* To show the human-readable values of used and available space in `/var/lib`, run the following command:
 +
 [source,terminal]
 ----

modules/storage-ephemeral-storage-overview.adoc

@@ -8,8 +8,7 @@
 [id=storage-ephemeral-storage-overview_{context}]
 = Overview
 
-Pods and containers are ephemeral or transient in nature and designed for stateless applications. Ephemeral storage allows administrators and developers to better manage the local storage for some of their operations.
-
+[role="_abstract"]
 In addition to persistent storage, pods and containers can require ephemeral or transient local storage for their operation. The lifetime of this ephemeral storage does not extend beyond the life of the individual pod, and this ephemeral storage cannot be shared across pods.
 
 Pods use ephemeral local storage for scratch space, caching, and logs. Issues related to the lack of local storage accounting and isolation include the following:

modules/storage-ephemeral-storage-types.adoc

@@ -7,16 +7,11 @@
 [id=storage-ephemeral-storage-types_{context}]
 = Types of ephemeral storage
 
-Ephemeral local storage is always made available in the primary
-partition. There are two basic ways of creating the primary
-partition: root and runtime.
+[role="_abstract"]
+Ephemeral local storage is always made available in the primary partition. 
 
+There are two basic ways of creating the primary partition:
 
-== Root
+* *Root*: This partition holds the kubelet root directory, `/var/lib/kubelet/` by default, and `/var/log/` directory. This partition can be shared between user pods, the OS, and Kubernetes system daemons. This partition can be consumed by pods through `EmptyDir` volumes, container logs, image layers, and container-writable layers. Kubelet manages shared access and isolation of this partition. This partition is ephemeral, and applications cannot expect any performance SLAs, such as disk IOPS, from this partition.
 
-This partition holds the kubelet root directory, `/var/lib/kubelet/` by default, and `/var/log/` directory. This partition can be shared between user pods, the OS, and Kubernetes system daemons. This partition can be consumed by pods through `EmptyDir` volumes, container logs, image layers, and container-writable layers. Kubelet manages shared access and isolation of this partition. This partition is ephemeral, and applications cannot expect any performance SLAs, such as disk IOPS, from this partition.
-
-
-== Runtime
-
-This is an optional partition that runtimes can use for overlay file systems. {product-title} attempts to identify and provide shared access along with isolation to this partition. Container image layers and writable layers are stored here. If the runtime partition exists, the `root` partition does not hold any image layer or other writable storage.
+* *Runtime*: This is an optional partition that runtimes can use for overlay file systems. {product-title} attempts to identify and provide shared access along with isolation to this partition. Container image layers and writable layers are stored here. If the runtime partition exists, the `root` partition does not hold any image layer or other writable storage.

storage/understanding-ephemeral-storage.adoc

@@ -1,8 +1,13 @@
 :_mod-docs-content-type: ASSEMBLY
 [id="understanding-ephemeral-storage"]
 = Understanding ephemeral storage
-include::_attributes/common-attributes.adoc[]
+:toc:
+:toc-title:
 :context: understanding-ephemeral-storage
+include::_attributes/common-attributes.adoc[]
+
+[role="_abstract"]
+Pods and containers are ephemeral or transient in nature and designed for stateless applications. Ephemeral storage allows administrators and developers to better manage the local storage for some of their operations.
 
 toc::[]