# Rehydration

> Rehydrate logs from cold storage to query historical data beyond your retention period

Source: https://last9.io/docs/control-plane-rehydration/

Rehydration allows you to retrieve logs from your cold storage back into Last9 for querying. This feature enables you to access historical log data that's beyond your organization's retention period.

Access the [Rehydration](https://app.last9.io/control-plane/rehydration) feature in your Last9 Control Plane.

![Rehydration Overview](../../../../../assets/content/docs/control-plane/storage/rehydration/new-rehydrated-index.png)

## Prerequisites

Before you can rehydrate logs, ensure that:

- [Cold Storage](/docs/control-plane-cold-storage/) is enabled for your organization

## Creating a Rehydrated Index

1. Navigate to [Rehydration](https://app.last9.io/control-plane/rehydration) in the Control Plane
2. Click **New Rehydrated Index** to open the configuration modal
3. Configure your rehydration settings:
   1. **Select Source**: Select from available indexes (typically "Default Index") ![Rehydration Source](../../../../../assets/content/docs/control-plane/storage/rehydration/new-1-select-source-index.png)
   2. **Add Definition**: ![Rehydration Definition](../../../../../assets/content/docs/control-plane/storage/rehydration/new-2-add-definition.png)
   - **Time Range**: Choose a time period from before your retention period. If your organization has a 14-day retention, you can only select dates older than 14 days
   - **Services to Rehydrate**: If service-level backup is enabled in your cold storage, you can select specific services to rehydrate instead of all logs
   - **Estimated Size**: Review the estimated compressed size of data to be rehydrated
   3. **Set Destination Details**: ![Rehydration Destinal](../../../../../assets/content/docs/control-plane/storage/rehydration/new-3-add-destination-details.png)
      - **Rehydrated Index Name**: Provide a descriptive name for easy identification
      - **Send Notification When Ready** (Optional): If you have email channels configured in your organization settings, you can enable notifications to receive updates when the rehydration job completes
4. Click **Rehydrate Index** to start the process

The rehydration job will appear in your index list with an "Index is being rehydrated" status.

## Understanding Rehydrated Index States

![Rehydration Overview](../../../../../assets/content/docs/control-plane/storage/rehydration/index-status.png)

Your rehydrated indexes can have several different states:

- **Index is being rehydrated**: Process is currently running
- **Available**: Index is ready for querying, shows availability window
- **Expired**: Index has passed its retention period and is no longer queryable
- **Failed**: Rehydration process encountered an error and needs to be retried

## Querying Rehydrated Data

Once your rehydration is complete and shows "Available" status:

1. Click the **View in Logs** button next to your rehydrated index
2. This opens the Log Explorer with:
   - Your rehydrated index pre-selected
   - Time range set to the last 5 minutes of your rehydrated data window
3. You can now modify the time range and apply filters to explore your rehydrated data
4. Click on Run Query or use the `cmd/ctrl + enter` shortcut

:::note
When querying a rehydrated index, the [time range picker](/docs/time-range-picker/) is restricted to the index's time window. You will only be able to select time periods that fall within the rehydrated data range.
:::

## Managing Rehydrated Indexes

Each rehydrated index includes management options accessible through the more (⋯) menu:

- **Rehydrate**: Create a new rehydration job for the same time period
- **Delete**: Remove the rehydrated index to free up storage

## Best Practices

- **Selective Rehydration**: When service-level backup is available, rehydrate only the services you need to reduce processing time and storage costs
- **Naming Convention**: Use descriptive names that include the date range and purpose, such as `incident_analysis_june_2025` or `compliance_audit_q1_2025`
- **Time Range Planning**: Remember that you can only rehydrate data from before your retention period. Plan accordingly when investigating incidents or conducting analysis

---

## Troubleshooting

- **Index Failed to Rehydrate**: If you see a "Failed — Rehydration Process Failed, Please Retry" message, select "Retry" from the more (⋯) menu or try creating a new rehydration job with the same parameters. If the issue persists, contact support
- **No Data Available**: Ensure your cold storage contains data for the selected time range and that the time range is before your retention period

Please get in touch with us on [Discord](https://discord.com/invite/Q3p2EEucx9) or [Email](mailto:support@last9.io) if you have any questions.