opensearch-docs-cn/_tuning-your-cluster/availability-and-recovery/snapshots/snapshot-restore.md

---
layout: default
title: Take and restore snapshots
parent: Snapshots
nav_order: 10
has_children: false
grand_parent: Availability and Recovery
redirect_from: 
  - /opensearch/snapshots/snapshot-restore/
  - /opensearch/snapshot-restore/
  - /availability-and-recovery/snapshots/snapshot-restore/
---

# Take and restore snapshots

Snapshots aren't instantaneous. They take time to complete and do not represent perfect point-in-time views of the cluster. While a snapshot is in progress, you can still index documents and send other requests to the cluster, but new documents and updates to existing documents generally aren't included in the snapshot. The snapshot includes primary shards as they existed when OpenSearch initiated the snapshot. Depending on the size of your snapshot thread pool, different shards might be included in the snapshot at slightly different times.

OpenSearch snapshots are incremental, meaning that they only store data that has changed since the last successful snapshot. The difference in disk usage between frequent and infrequent snapshots is often minimal.

In other words, taking hourly snapshots for a week (for a total of 168 snapshots) might not use much more disk space than taking a single snapshot at the end of the week. Also, the more frequently you take snapshots, the less time they take to complete. Some OpenSearch users take snapshots as often as every 30 minutes.

If you need to delete a snapshot, be sure to use the OpenSearch API rather than navigating to the storage location and purging files. Incremental snapshots from a cluster often share a lot of the same data; when you use the API, OpenSearch only removes data that no other snapshot is using.
{: .tip }

---

#### Table of contents
1. TOC
{:toc}


---


## Register repository

Before you can take a snapshot, you have to "register" a snapshot repository. A snapshot repository is just a storage location: a shared file system, Amazon S3, Hadoop Distributed File System (HDFS), Azure Storage, etc.


### Shared file system

1. To use a shared file system as a snapshot repository, add it to `opensearch.yml`:

   ```yml
   path.repo: ["/mnt/snapshots"]
   ```

   On the RPM and Debian installs, you can then mount the file system. If you're using the Docker install, add the file system to each node in `docker-compose.yml` before starting the cluster:

   ```yml
   volumes:
     - /Users/jdoe/snapshots:/mnt/snapshots
   ```

1. Then register the repository using the REST API:

   ```json
   PUT /_snapshot/my-fs-repository
   {
     "type": "fs",
     "settings": {
       "location": "/mnt/snapshots"
     }
   }
   ```
  {% include copy-curl.html %}

You will most likely not need to specify any parameters except for `location`. For allowed request parameters, see [Register or update snapshot repository API](https://opensearch.org/docs/latest/api-reference/snapshots/create-repository/).

### Amazon S3

1. To use an Amazon S3 bucket as a snapshot repository, install the `repository-s3` plugin on all nodes:

   ```bash
   sudo ./bin/opensearch-plugin install repository-s3
   ```

   If you're using the Docker installation, see [Working with plugins]({{site.url}}{{site.baseurl}}/opensearch/install/docker#working-with-plugins). Your `Dockerfile` should look something like this:

   ```
   FROM opensearchproject/opensearch:{{site.opensearch_version}}

   ENV AWS_ACCESS_KEY_ID <access-key>
   ENV AWS_SECRET_ACCESS_KEY <secret-key>

   # Optional
   ENV AWS_SESSION_TOKEN <optional-session-token>

   RUN /usr/share/opensearch/bin/opensearch-plugin install --batch repository-s3
   RUN /usr/share/opensearch/bin/opensearch-keystore create

   RUN echo $AWS_ACCESS_KEY_ID | /usr/share/opensearch/bin/opensearch-keystore add --stdin s3.client.default.access_key
   RUN echo $AWS_SECRET_ACCESS_KEY | /usr/share/opensearch/bin/opensearch-keystore add --stdin s3.client.default.secret_key

   # Optional
   RUN echo $AWS_SESSION_TOKEN | /usr/share/opensearch/bin/opensearch-keystore add --stdin s3.client.default.session_token
   ```

   After the Docker cluster starts, skip to step 7.

1. Add your AWS access and secret keys to the OpenSearch keystore:

   ```bash
   sudo ./bin/opensearch-keystore add s3.client.default.access_key
   sudo ./bin/opensearch-keystore add s3.client.default.secret_key
   ```

1. (Optional) If you're using temporary credentials, add your session token:

   ```bash
   sudo ./bin/opensearch-keystore add s3.client.default.session_token
   ```

1. (Optional) If you connect to the internet through a proxy, add those credentials:

   ```bash
   sudo ./bin/opensearch-keystore add s3.client.default.proxy.username
   sudo ./bin/opensearch-keystore add s3.client.default.proxy.password
   ```

1. (Optional) Add other settings to `opensearch.yml`:

   ```yml
   s3.client.default.disable_chunked_encoding: false # Disables chunked encoding for compatibility with some storage services, but you probably don't need to change this value.
   s3.client.default.endpoint: s3.amazonaws.com # S3 has alternate endpoints, but you probably don't need to change this value.
   s3.client.default.max_retries: 3 # number of retries if a request fails
   s3.client.default.path_style_access: false # whether to use the deprecated path-style bucket URLs.
   # You probably don't need to change this value, but for more information, see https://docs.aws.amazon.com/AmazonS3/latest/dev/VirtualHosting.html#path-style-access.
   s3.client.default.protocol: https # http or https
   s3.client.default.proxy.host: my-proxy-host # the hostname for your proxy server
   s3.client.default.proxy.port: 8080 # port for your proxy server
   s3.client.default.read_timeout: 50s # the S3 connection timeout
   s3.client.default.use_throttle_retries: true # whether the client should wait a progressively longer amount of time (exponential backoff) between each successive retry
   s3.client.default.region: us-east-2 # AWS region to use
   ```

1. (Optional) If you don't want to use AWS access and secret keys, you could configure the S3 plugin to use AWS Identity and Access Management (IAM) roles for service accounts:

   ```bash
   sudo ./bin/opensearch-keystore add s3.client.default.role_arn
   sudo ./bin/opensearch-keystore add s3.client.default.role_session_name
   ```

   If you don't want to configure AWS access and secret keys, modify the following `opensearch.yml` setting. Make sure the file is accessible by the `repository-s3` plugin:
   
   ```yml
   s3.client.default.identity_token_file: /usr/share/opensearch/plugins/repository-s3/token
   ```

   If copying is not an option, you can create a symlink to the web identity token file in the `${OPENSEARCH_PATH_CONFIG}` folder:

   ```
   ln -s $AWS_WEB_IDENTITY_TOKEN_FILE "${OPENSEARCH_PATH_CONFIG}/aws-web-identity-token-file"
   ```

   You can reference the web identity token file in the following `opensearch.yml` setting by specifying the relative path that is resolved against `${OPENSEARCH_PATH_CONFIG}`:

   ```yaml
   s3.client.default.identity_token_file: aws-web-identity-token-file
   ```

   IAM roles require at least one of the above settings. Other settings will be taken from environment variables (if available): `AWS_ROLE_ARN`, `AWS_WEB_IDENTITY_TOKEN_FILE`, `AWS_ROLE_SESSION_NAME`.

1. If you changed `opensearch.yml`, you must restart each node in the cluster. Otherwise, you only need to reload secure cluster settings:

   ```
   POST /_nodes/reload_secure_settings
   ```
  {% include copy-curl.html %}

1. Create an S3 bucket if you don't already have one. To take snapshots, you need permissions to access the bucket. The following IAM policy is an example of those permissions:

   ```json
   {
	   "Version": "2012-10-17",
	   "Statement": [{
		   "Action": [
			   "s3:*"
		   ],
		   "Effect": "Allow",
		   "Resource": [
			   "arn:aws:s3:::your-bucket",
			   "arn:aws:s3:::your-bucket/*"
		   ]
	   }]
   }
   ```

1. Register the repository using the REST API:

   ```json
   PUT /_snapshot/my-s3-repository
   {
     "type": "s3",
     "settings": {
       "bucket": "my-s3-bucket",
       "base_path": "my/snapshot/directory"
     }
   }
   ```
   {% include copy-curl.html %}

You will most likely not need to specify any parameters except for `bucket` and `base_path`. For allowed request parameters, see [Register or update snapshot repository API](https://opensearch.org/docs/latest/api-reference/snapshots/create-repository/).

## Take snapshots

You specify two pieces of information when you create a snapshot:

- Name of your snapshot repository
- Name for the snapshot

The following snapshot includes all indices and the cluster state:

```json
PUT /_snapshot/my-repository/1
```
{% include copy-curl.html %}

You can also add a request body to include or exclude certain indices or specify other settings:

```json
PUT /_snapshot/my-repository/2
{
  "indices": "opensearch-dashboards*,my-index*,-my-index-2016",
  "ignore_unavailable": true,
  "include_global_state": false,
  "partial": false
}
```
{% include copy-curl.html %}

Request fields | Description
:--- | :---
`indices` | The indices you want to include in the snapshot. You can use `,` to create a list of indices, `*` to specify an index pattern, and `-` to exclude certain indices. Don't put spaces between items. Default is all indices.
`ignore_unavailable` | If an index from the `indices` list doesn't exist, whether to ignore it rather than fail the snapshot. Default is false.
`include_global_state` | Whether to include cluster state in the snapshot. Default is true.
`partial` | Whether to allow partial snapshots. Default is false, which fails the entire snapshot if one or more shards fails to store.

If you request the snapshot immediately after taking it, you might see something like this:

```json
GET /_snapshot/my-repository/2
{
  "snapshots": [{
    "snapshot": "2",
    "version": "6.5.4",
    "indices": [
      "opensearch_dashboards_sample_data_ecommerce",
      "my-index",
      "opensearch_dashboards_sample_data_logs",
      "opensearch_dashboards_sample_data_flights"
    ],
    "include_global_state": true,
    "state": "IN_PROGRESS",
    ...
  }]
}
```
{% include copy-curl.html %}

Note that the snapshot is still in progress. If you want to wait for the snapshot to finish before continuing, add the `wait_for_completion` parameter to your request. Snapshots can take a while to complete, so consider whether or not this option fits your use case:

```
PUT _snapshot/my-repository/3?wait_for_completion=true
```
{% include copy-curl.html %}

Snapshots have the following states:

State | Description
:--- | :---
SUCCESS | The snapshot successfully stored all shards.
IN_PROGRESS | The snapshot is currently running.
PARTIAL | At least one shard failed to store successfully. Can only occur if you set `partial` to `true` when taking the snapshot.
FAILED | The snapshot encountered an error and stored no data.
INCOMPATIBLE | The snapshot is incompatible with the version of OpenSearch running on this cluster. See [Conflicts and compatibility](#conflicts-and-compatibility).

You can't take a snapshot if one is currently in progress. To check the status:

```
GET /_snapshot/_status
```
{% include copy-curl.html %}


## Restore snapshots

The first step in restoring a snapshot is retrieving existing snapshots. To see all snapshot repositories:

```
GET /_snapshot/_all
```
{% include copy-curl.html %}

To see all snapshots in a repository:

```
GET /_snapshot/my-repository/_all
```
{% include copy-curl.html %}

Then restore a snapshot:

```
POST /_snapshot/my-repository/2/_restore
```
{% include copy-curl.html %}

Just like when taking a snapshot, you can add a request body to include or exclude certain indices or specify some other settings:

```json
POST /_snapshot/my-repository/2/_restore
{
  "indices": "opensearch-dashboards*,my-index*",
  "ignore_unavailable": true,
  "include_global_state": false,
  "include_aliases": false,
  "partial": false,
  "rename_pattern": "opensearch-dashboards(.+)",
  "rename_replacement": "restored-opensearch-dashboards$1",
  "index_settings": {
    "index.blocks.read_only": false
  },
  "ignore_index_settings": [
    "index.refresh_interval"
  ]
}
```
{% include copy-curl.html %}

Request parameters | Description
:--- | :---
`indices` | The indices you want to restore. You can use `,` to create a list of indices, `*` to specify an index pattern, and `-` to exclude certain indices. Don't put spaces between items. Default is all indices.
`ignore_unavailable` | If an index from the `indices` list doesn't exist, whether to ignore it rather than fail the restore operation. Default is false.
`include_global_state` | Whether to restore the cluster state. Default is false.
`include_aliases` | Whether to restore aliases alongside their associated indices. Default is true.
`partial` | Whether to allow the restoration of partial snapshots. Default is false.
`rename_pattern` | If you want to rename indices as you restore them, use this option to specify a regular expression that matches all indices you want to restore. Use capture groups (`()`) to reuse portions of the index name.
`rename_replacement` | If you want to rename indices as you restore them, use this option to specify the replacement pattern. Use `$0` to include the entire matching index name, `$1` to include the content of the first capture group, etc.
`index_settings` | If you want to change [index settings]({{site.url}}{{site.baseurl}}/api-reference/index-apis/create-index/#index-settings) applied during restore, specify them here. You cannot change `index.number_of_shards`.
`ignore_index_settings` | Rather than explicitly specifying new settings with `index_settings`, you can ignore certain index settings in the snapshot and use the cluster defaults applied during restore. You cannot ignore `index.number_of_shards`, `index.number_of_replicas`, or `index.auto_expand_replicas`.
`storage_type` | `local` indicates that all snapshot metadata and index data will be downloaded to local storage. <br /><br > `remote_snapshot` indicates that snapshot metadata will be downloaded to the cluster, but the remote repository will remain the authoritative store of the index data. Data will be downloaded and cached as necessary to service queries. At least one node in the cluster must be configured with the [search role]({{site.url}}{{site.baseurl}}/security/access-control/users-roles/) in order to restore a snapshot using the type `remote_snapshot`. <br /><br > Defaults to `local`.

### Conflicts and compatibility

One way to avoid naming conflicts when restoring indices is to use the `rename_pattern` and `rename_replacement` options. Then, if necessary, you can use the `_reindex` API to combine the two. The simpler way is to delete existing indices prior to restoring from a snapshot.

You can use the `_close` API to close existing indices prior to restoring from a snapshot, but the index in the snapshot has to have the same number of shards as the existing index.

We recommend ceasing write requests to a cluster before restoring from a snapshot, which helps avoid scenarios such as:

1. You delete an index, which also deletes its alias.
1. A write request to the now-deleted alias creates a new index with the same name as the alias.
1. The alias from the snapshot fails to restore due to a naming conflict with the new index.

Snapshots are only forward-compatible by one major version. If you have an old snapshot, you can sometimes restore it into an intermediate cluster, reindex all indices, take a new snapshot, and repeat until you arrive at your desired version, but you might find it easier to just manually index your data on the new cluster.

## Security considerations

If you're using the Security plugin, snapshots have some additional restrictions:

- To perform snapshot and restore operations, users must have the built-in `manage_snapshots` role.
- You can't restore snapshots that contain global state or the `.opendistro_security` index.

If a snapshot contains global state, you must exclude it when performing the restore. If your snapshot also contains the `.opendistro_security` index, either exclude it or list all the other indices you want to include:

```json
POST /_snapshot/my-repository/3/_restore
{
  "indices": "-.opendistro_security",
  "include_global_state": false
}
```
{% include copy-curl.html %}

The `.opendistro_security` index contains sensitive data, so we recommend excluding it when you take a snapshot. If you do need to restore the index from a snapshot, you must include an admin certificate in the request:

```bash
curl -k --cert ./kirk.pem --key ./kirk-key.pem -XPOST 'https://localhost:9200/_snapshot/my-repository/3/_restore?pretty'
```
{% include copy-curl.html %}

We strongly recommend against restoring `.opendistro_security` using an admin certificate because doing so can alter the security posture of the entire cluster. See [A word of caution]({{site.url}}{{site.baseurl}}/security-plugin/configuration/security-admin/#a-word-of-caution) for a recommended process to back up and restore your Security plugin configuration.
{: .warning}