update kuber doc: stroage

2025-07-23 14:52:27 +03:30
parent e41aa509c6
commit 26d00e355d
5 changed files with 64 additions and 12 deletions
--- a/Orchestration/Kubernetes/Storage/Pv.md
+++ b/Orchestration/Kubernetes/Storage/Pv.md
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+# 🌐 Kubernetes Persistent Volumes (PV) Cheat Sheet
+
+## 📦 What is a Persistent Volume (PV)?
+
+A **Persistent Volume (PV)** is a piece of storage in a Kubernetes cluster that is either:
+
+* Pre-provisioned by an administrator, or
+* Dynamically provisioned using **StorageClasses**.
+
+It allows data to **persist beyond the lifecycle of individual Pods**.
+
+---
+
+## 📁 PV Storage Options
+
+1. **HostPath**
+
+   * Mounts a file or directory from the host node’s filesystem into your Pod.
+   * Useful only for single-node testing or development.
+
+2. **Using PV and PVC**
+
+   * **PV (Persistent Volume):** Represents the actual storage resource.
+   * **PVC (Persistent Volume Claim):** A user's request for storage resources and access.
+
+---
+
+## 🧱 Kubernetes Storage Layers
+
+1. **Persistent Volume (PV)** – The actual storage unit.
+2. **Persistent Volume Claim (PVC)** – A request for that storage.
+
+---
+
+## 🔄 PV Lifecycle States
+
+| State        | Description                                |
+| ------------ | ------------------------------------------ |
+| Provisioning | PV is being prepared.                      |
+| Binding      | PV is bound to a PVC.                      |
+| Using        | PV is in use by a Pod.                     |
+| Releasing    | PVC is deleted; PV becomes unbound.        |
+| Reclaiming   | Reclaim policy is applied:                 |
+|              | • `Delete` – Remove the storage.           |
+|              | • `Recycle` – Basic scrub (deprecated).    |
+|              | • `Retain` – Manual intervention required. |
+
+---
+
+## 🔒 PV Access Modes
+
+| Mode   | Description                                    |
+| ------ | ---------------------------------------------- |
+| `RWO`  | **ReadWriteOnce** – One node can read/write    |
+| `ROX`  | **ReadOnlyMany** – Multiple nodes read-only    |
+| `RWX`  | **ReadWriteMany** – Multiple nodes read/write  |
+| `RWOP` | **ReadWriteOncePod** – Only one Pod can use it |
+
+---
+
+## 🛠️ CLI Commands to Manage PVs
+
+```bash
+# List all Persistent Volumes
+kubectl get pv
+
+# List all Persistent Volume Claims
+kubectl get pvc
+
+# Edit a PVC
+kubectl edit pvc -n <namespace> <pvc-name>
+```
+
+---
+
+## 🚀 Example 1: Deployment with `hostPath` Volume
+
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: app-1
+  namespace: dev
+  labels:
+    app.kubernetes.io/name: nginx
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: nginx
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: nginx
+    spec:
+      containers:
+        - name: nginx
+          image: nginx
+          ports:
+            - containerPort: 80
+          volumeMounts:
+            - name: nginx-log
+              mountPath: /var/log/nginx
+      volumes:
+        - name: nginx-log
+          hostPath:
+            path: /root/nginx/logs
+            type: DirectoryOrCreate
+```
+
+
+---
+
+## 📂 Example 2: NFS-backed Persistent Volume
+
+### 🧩 PersistentVolume Definition
+
+```yaml
+apiVersion: v1
+kind: PersistentVolume
+metadata:
+  name: pv1
+spec:
+  capacity:
+    storage: 5Gi
+  volumeMode: Filesystem
+  accessModes:
+    - ReadWriteMany
+  persistentVolumeReclaimPolicy: Retain
+  storageClassName: custom-name
+  mountOptions:
+    - hard
+    - nfsvers=4.1
+  nfs:
+    path: /nfs/data
+    server: 192.168.1.10
+```
+
+### 📄 PersistentVolumeClaim
+
+```yaml
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: pvc1
+  namespace: ns-test
+spec:
+  accessModes:
+    - ReadWriteMany
+  resources:
+    requests:
+      storage: 1Gi
+  storageClassName: custom-name
+```
+
+### 🚀 Deployment Using PVC
+
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: app-1
+  namespace: dev
+  labels:
+    app.kubernetes.io/name: nginx
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: nginx
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: nginx
+    spec:
+      containers:
+        - name: nginx
+          image: nginx
+          ports:
+            - containerPort: 80
+          volumeMounts:
+            - name: nginx-log
+              mountPath: /var/log/nginx
+      volumes:
+        - name: nginx-log
+          persistentVolumeClaim:
+            claimName: pvc1
+```
+
+---
+
+## 📝 Common Mistakes Fixed
+