# Automating snapshots with Snapshot Management
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You can set up a Snapshot Management (SM) policy in OpenSearch Dashboards to automate periodic snapshot creation and deletion. SM can snapshot of a group of indices, whereas [Index State Management](managedomains-snapshots.md#managedomains-snapshot-ism) can only take one snapshot per index. To use SM in OpenSearch Service, you need to register your own Amazon S3 repository. For instructions to register your repository, see [Registering a manual snapshot repository](https://docs.amazonaws.cn/opensearch-service/latest/developerguide/managedomains-snapshots.html#managedomains-snapshot-registerdirectory).

**Note**  
Snapshot Management is supported starting with OpenSearch version 2.5. Domains running earlier versions do not support this feature.

Prior to SM, OpenSearch Service offered a free, automated snapshot feature that's still turned on by default. This feature sends snapshots into the service-maintained `cs-*` repository. To deactivate the feature, reach out to Amazon Web Services Support. 

For more information on the SM feature, see [Snapshot management](https://opensearch.org/docs/latest/dashboards/sm-dashboards/) in the OpenSearch documentation.

SM doesn't currently support snapshot creation on multiple index types. For example, if you try to create snapshot on multiple indices with `*` and some indices are in the [warm tier](https://docs.amazonaws.cn/opensearch-service/latest/developerguide/ultrawarm.html#ultrawarm-manual-snapshot), the snapshot creation will fail. If you need your snapshot to contain multiple index types, use the [ISM snapshot action](https://opensearch.org/docs/latest/im-plugin/ism/policies/#snapshot) until SM supports this option.

## Considerations
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Consider the following when you configure snapshot management:
+ One policy is allowed per repository.
+ Up to 400 snapshots are allowed for one policy.
+ This feature won't run if your domain has a red status, is under high JVM pressure (85% or above), or has a stuck snapshot function. When the overall indexing and searching performance of your cluster is impacted, SM may also be impacted.
+ A snapshot operation only starts after the previous operation finishes, so that no concurrent snapshot operations are activated by one policy.
+ Multiple policies with the same schedule can cause a resource spike. If the policies' snapshotted indices overlap, the shard-level snapshot operations can only run sequentially, which can cause a cascaded performance problem. If the policies share a repository, there will be spike of write operations to that repository.
+ We recommend that you schedule your snapshot operations automation to no more than once per hour, unless you have a special use case.