update kuber doc: stroage

Containerization & Orchestration/Kubernetes/Storage/emptydir_vol.md

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+
+## 📦 Pod Volume Lifecycle & `emptyDir` Usage in Kubernetes
+
+This document describes how volumes work in the context of Kubernetes Pods, focusing on `emptyDir` and its lifecycle behavior.
+
+---
+
+### 🔁 Pod Lifecycle & Volumes
+
+* **Volumes are defined at the Pod level.**
+  They are not tied to a specific container, but can be shared among containers within the same Pod.
+
+* **Volumes are attached to containers through `volumeMounts`.**
+  This enables containers to access the volume’s filesystem at the specified `mountPath`.
+
+* **Data in `emptyDir` volumes is ephemeral.**
+  The volume is created when the Pod starts and **deleted when the Pod is removed**, erasing all stored data.
+
+---
+
+### ⚠️ Visibility Across Pods & Containers
+
+* A **Pod cannot access another Pod’s volume**, even if it's of type `emptyDir`.
+  For example:
+
+  * Pod A cannot see Pod B’s `emptyDir`.
+* However, **containers within the same Pod can share and access the same `emptyDir`** volume.
+
+---
+
+### 🧪 Example: Pod with `emptyDir` Volume in Memory
+
+```yaml
+apiVersion: v1
+kind: Pod
+metadata:
+  namespace: ns-test
+  name: pod-tests
+spec:
+  containers:
+    - name: nginx
+      image: nginx
+      resources:
+        limits:
+          memory: "150Mi"
+          cpu: "500m"
+      volumeMounts:
+        - name: nginx-log
+          mountPath: /var/log/nginx
+  volumes:
+    - name: nginx-log
+      emptyDir:
+        medium: Memory  # Uses memory for faster read/write operations
+        sizeLimit: 64Mi # Volume size limited to 64Mi
+```
+
+---
+
+### 🧠 Key Points
+
+* `emptyDir` is ideal for temporary storage like logs, scratch space, or caches.
+* Using `medium: Memory` stores data in memory (RAM) instead of disk, offering higher performance.
+* `sizeLimit` restricts the amount of memory that the `emptyDir` can consume.
+