Add user documentation for the node backupPVC and restorePVC (#1730)

Signed-off-by: Michal Pryc <[email protected]>

Author: mpryc

docs/data_mover_backup_pvc_configuration.md

@@ -0,0 +1,70 @@
+# Advanced Configuration for the Data Movement
+
+This guide provides instructions for configuring intermediate PVC behavior used during backup and restore workflows in OADP via the Data Protection Application (DPA) Custom Resource Definition (CRD).
+
+The settings introduced here provide control over how NodeAgent handles intermediate persistent volumes used in data movement operations.
+
+The following sections describe how to configure:
+
+- `backupPVC`
+- `restorePVC`
+
+These settings are defined under the `.spec.configuration.nodeAgent` section of the DPA CRD.
+
+---
+
+## 1. Configuring backupPVC for Snapshot Data Movement
+
+The `backupPVC` field allows you to define behavior for intermediate PVCs used during snapshot-to-object-store data movement. You can configure multiple storage classes, each with specific parameters.
+
+Each storage class block within backupPVC supports the following fields:
+
+- `storageClass` – the name of the storage class to use for the intermediate PVC.
+- `readOnly` – indicates if the PVC should be mounted as read-only. In some storage providers this can significantly reduce the performance when creating the backup from the snapshot. Setting this option to true requires `spcNoRelabeling` to be set to true as well.
+- `spcNoRelabeling` – disables automatic relabeling of the SecurityContextConstraints if set to true. It must be set to true when `readOnly` is set to true.
+
+Please refer to the Velero documentation for more details on the `backupPVC` feature. In the OADP project, this feature is controlled via the `nodeAgent.backupPVC` field in the DPA CRD, not through a ConfigMap. The latter is automatically created and managed by the OADP controller for you: [BackupPVC Configuration for Data Movement Backup](https://velero.io/docs/main/data-movement-backup-pvc-configuration/).
+
+
+Example Configuration
+
+The following example configures two storage classes: `gp3-csi` and `another-storage-class`. The gp3-csi PVC is mounted read-write, while `another-storage-class` is mounted read-only.
+
+```yaml
+spec:
+  configuration:
+    nodeAgent:
+      enable: true
+      backupPVC:
+        another-storage-class:
+          readOnly: true
+          spcNoRelabeling: true # required when readOnly is true
+          storageClass: gp3-csi
+        gp3-csi:
+          readOnly: false
+          spcNoRelabeling: false
+          storageClass: gp3-csi
+```
+
+
+
+## 2. Configuring restorePVC for Snapshot Data Movement
+
+The `restorePVC` field sets the behavior of intermediate PVCs used during restore operations. Currently, it supports a single option:
+
+- `ignoreDelayBinding` – when set to true, the data movement restore will bypass waiting for storage with WaitForFirstConsumer binding mode and proceed with restore PVC scheduling.
+
+This can help avoid delays in cluster environments with custom scheduler configurations or in cases where prompt restore is preferred.
+
+Example Configuration
+
+```yaml
+spec:
+  configuration:
+    nodeAgent:
+      enable: true
+      restorePVC:
+        ignoreDelayBinding: true
+```
+
+Please refer to the Velero documentation for more details on the `restorePVC` feature. In the OADP project, this feature is controlled via the `nodeAgent.restorePVC` field in the DPA CRD, not through a ConfigMap. The latter is automatically created and managed by the OADP controller for you: [RestorePVC Configuration for Data Movement Restore](https://velero.io/docs/v1.16/data-movement-restore-pvc-configuration/).