# HyperScale Reference Architecture - Recovering a Node

When there are hardware failures in a HyperScale node, such as disk issues or corrupted operating system, only the drive containing the operating system can be recovered. Drives containing the backup and other data, such as the Deduplication Database (DDB) and Index Cache can be preserved.

## Before You Begin

Perform the following steps if the node was setup using Service Pack 9:

- Login to the node and navigate to the following folder:

  `/opt/commvault/Base`

- Run the following command:

  `./CVSDS -r`

  This command will enumerate all data disk drives and stamp the missing extended attributes.

## Procedure

1. Follow the steps described in Setting Up HyperScale Storage Nodes to re-image the node.

   Note

   Make sure to select the Preserve drives option when you start the imaging process, to preserve the drives containing the backup data as well as the DDB and Index Cache.

2. Once the nodes are re-imaged, reconfigure the nodes using the steps described in Setting Up HyperScale Storage Nodes with the network settings and CommServe related information.

3. Once the node is re-imaged and re-configured, open the CommCell Console and perform a readiness check and verify that the node is accessible. See Viewing the Check Readiness Report for more information on performing the readiness check.

   Perform the following steps if the readiness fails:

   1. Delete contents of `/opt/commvault/Base/certificates` folder in the node.

   2. Revoke the active certificates for the client (node) as described in Revoking a Client Certificate.

   3. Create a temporary certificate and renew the certificate as described in Renew a Revoked Certificate.

      Make sure to copy and paste the renewed certificate in the `/opt/commvault/Base/certificates/export.txt` file.

   4. Restart the services on the node. See Controlling Services on UNIX for more information on restarting services.

   5. Add the necessary host entries for the node in the other 2 MediaAgents to the `/etc/hosts` file.

4. Open the CommCell Console and add the MMEnableStoragepoolNodeRefresh additional setting with the value 1. The additional setting must be created on the CommServe. See Adding or Modifying Additional Settings for more information.

   This additional setting will enable the Refresh option for the storage pool in the Command Center.

5. Open the Command Center and navigate to Storage > Storage Pools.

6. From the Storage Pools page, click the name of the <Storage Pool> in which the reconstructed node is located.

7. In the Storage area, click the Actions button against the reconstructed node, and then click Refresh. Click Confirm.

   This will refresh the node and the node will be displayed as Ready in the Status column.

8. Verify that the node is refreshed. Check the following details:

   - Storage target state, total capacity, and mount path status

     Execute the following commands:

         df -ht fuse.glusterfs
         mount|grep fuse

   - Deduplication database summary and details.

   - Node status and the respective drives state.

   If the Index Cache is not up to date, it will be reconstructed automatically as part of any operations which queries the index, such as backup, browse, find.

   Similarly, if the DDB is detected as offline, unreadable, or unavailable, it will automatically recovered from the latest DDB backup.

9. Recommended: Open the CommCell Console and disable the MMEnableStoragepoolNodeRefresh additional setting, by setting the value to 0.

10. Enable ransomware protection for the node.

## Related Topics

- Saving the Configuration

- Restoring the Saved Configuration

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