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+# Upgrade Vald cluster
+
+Before this document, we recommend reading [the configuration document](../user-guides/configuration.md) first.
+
+## Update Configuration
+
+When you'd like to update the configuration for the Vald cluster, you need to edit your configuration file and apply it according to your deployment method.
+Please refer to one of the sections below according to your deployment method.
+
+<div class="caution">
+If each Vald Agent already has the indexes and uses the backup feature, please DO NOT edit the dimension and the distance type to avoid initContainer error.<BR>
+(Each Vald Agent will restore from backup data when performing a rolling update)
+</div>
+
+<div class="warn">
+The indexes will be clear when performing a rolling update if each Vald Agent already has the indexes and the backup feature disabled.
+</div>
+
+### Using Helm for deployment
+
+The configuration file is `values.yaml`. ([Helm Values](https://helm.sh/docs/chart_template_guide/values_files/))
+
+You can edit your `values.yaml` and update your Vald cluster by following steps:
+
+1. Edit `values.yaml`.
+1. Update with Helm command.
+
+   ```bash
+   helm upgrade <NAME> vald/vald --values <YOUR VALUES FILE PATH>
+   # e.g., helm upgrade vald vald/vald --values valeus.yaml
+   ```
+
+### Using vald-helm-operator
+
+There are two configuration files:
+
+- `vhor.yaml` for vald-helm-operator
+- `vr.yaml` for the Vald cluster
+
+If you don't need to update the `vald-helm-operator`, please skip step.1 and step.2.
+The Vald cluster will be updated by the following steps:
+
+1. Edit `vhor.yaml`.
+1. Apply `vhor.yaml`.
+
+   ```bash
+   kubectl apply -f <VHOR YAML FILE PATH>
+   # e.g., kubectl apply -f vhor.yaml
+   ```
+
+1. Edit `vr.yaml`.
+1. Apply `vr.yaml`.
+
+   ```bash
+   kubectl apply -f <VR YAML FILE PATH>
+   # e.g., kubectl apply -f vr.yaml
+   ```
+
+## Upgrade Vald version
+
+We recommend using the latest Vald version.
+
+If your Vald cluster uses an old version and you'd like to upgrade the Vald version, you can upgrade by the following sections.
+Please refer to one of the sections below according to your deployment method.
+
+<div class="caution">
+When the upgrade request is applied, Kubernetes will perform a rolling update.
+If your Vald cluster does not apply backup, the index will be cleared by a rolling update.<BR>
+In addition, if each Vald Agent already has the indexes and the backup feature enabled, please DO NOT edit the dimension and the distance type to avoid initContainer error.
+(Each Vald Agent will restore from backup data when backup when performing a rolling update)
+</div>
+
+### Using Helm for deployment
+
+Using the `Helm` command for the deployment of the Vald cluster, the upgrading steps are below.
+
+<div class="warn">
+Before upgrading, please confirm your Vald cluster version.<BR>
+If there is major or minor upgrading, the chart structure may have changed.
+</div>
+
+1. Verify vald repo in your helm repo
+
+   ```bash
+   helm repo list
+   ```
+
+1. Update Helm repo
+
+   ```bash
+   helm repo update <NAME of Vald>
+   # e.g., helm repo update vald
+   ```
+
+1. Edit `values.yaml`
+
+   - We recommend setting a specific version as an image tag.
+
+     ```yaml
+     defaults:
+     ---
+     image:
+       tag: v1.5.6 # set a new version
+     ```
+
+1. Apply `values.yaml`
+
+   ```bash
+   helm upgrade <NAME> vald/vald --values <YOUR VALUES FILE PATH>
+   # e.g., helm upgrade vald vald/vald --values valeus.yaml
+   ```
+
+### Using vald-helm-operator
+
+The upgrading steps are below if you use `vald-helm-operator` for the deployment.
+
+1. Upgrade CRDs
+
+   ```bash
+   kubectl replace -f https://raw.githubusercontent.com/vdaas/vald/<VERSION>/charts/vald-helm-operator/crds/valdrelease.yaml
+   kubectl replace -f https://raw.githubusercontent.com/vdaas/vald/<VERSION>/charts/vald-helm-operator/crds/valdhelmoperatorrelease.yaml
+   ```
+
+1. Update `vhor`
+
+   ```bash
+   kubectl patch vhor vhor-release -p '{"spec":{"image":{"tag":"<VERSION>"}}}'
+   ```
+
+   - Also, you can upgrade manually by editing `vhor.yaml` and applying it.
+
+1. Edit `vr.yaml`
+
+   - We recommend setting a specific version as an image tag.
+
+     ```yaml
+     ...
+     spec:
+       defaults:
+         ...
+         image:
+           tag: v1.5.6 # set a new version
+         ...
+     ```
+
+1. Apply `vr.yaml`
+
+   ```bash
+   kubectl apply -f <VR YAML FILE PATH>
+   # e.g., kubectl apply -f vr.yaml
+   ```