Can a Deleted CSS Cluster Be Restored?

Yes. You can use a snapshot stored in OBS to restore a cluster. A deleted cluster that has no snapshots in OBS cannot be restored. Exercise caution when deleting a cluster.

To restore a deleted cluster using one of its snapshots stored in OBS, perform the following steps:

1. Log in to the CSS management console.
2. Click Create Cluster in the upper right corner to create a cluster. During the cluster creation, disable the cluster snapshot function. After the cluster is created, enable the cluster snapshot function.
   

   To restore a deleted cluster to a new cluster, ensure they are in the same region. The new cluster version must be the same as or later than that of the deleted cluster. The quantity of nodes in the new cluster must be greater than half of that in the deleted cluster. Otherwise, the cluster may fail to be restored.

3. If the status of the new cluster changes to Available, click the cluster name to go to the Cluster Information page.
4. In the navigation pane on the left, choose Cluster Snapshots. Enable the cluster snapshot function. Set the OBS bucket and backup path to those set for the cluster that needs to be restored.

   After the configuration is saved, you can view the snapshot information of the deleted cluster in the snapshot management list a few minutes later. If the snapshot is not displayed, edit the basic snapshot configuration again, change the backup path to another one and then to the correct one, save the modification, and try again.

   

   To restore the data of a deleted cluster to an existing cluster, set the OBS bucket and backup path to those of the deleted cluster.

5. Locate the target snapshot and click Restore in the Operation column. The Restore page is displayed.
   Figure 1 Selecting a snapshot
   
6. On the Restore page, set restoration parameters.

   Table 1 Restoration settings

   Parameter	Description
   Index	Enter the name of the index you want to restore. If you do not specify any index name, the data of all indexes will be restored. This parameter is left blank by default. The value can contain 0 to 1024 characters, and cannot contain spaces, uppercase letters, or the following special characters: "\<|>/?. You can use the asterisk (*) to match multiple indexes. For example, index* indicates that all indexes with the prefix index will be restored.
   Rename Pattern	Enter a regular expression. Indexes that match the regular expression will be restored. The default value index_(.+) indicates all indexes. The value can contain 0 to 1024 characters, and cannot contain spaces, uppercase letters, or the following special characters: "\<|>/?,. NOTE: The Rename Pattern and Rename Replacement take effect only when they are both configured at the same time.
   Rename Replacement	Rule for index renaming. The default value restored_index_$1 indicates that restored_ will be added to the beginning of the names of all restored indexes. The value can contain 0 to 1024 characters, and cannot contain spaces, uppercase letters, or the following special characters: "\<|>/?,. NOTE: The Rename Pattern and Rename Replacement take effect only when they are both configured at the same time.
   Cluster	Select the cluster where you want to restore the data to. You can select the current cluster or another. You must specify a cluster whose status is Available. If the status of the current cluster is Unavailable, you cannot restore the snapshot to the current cluster. When restoring data to another cluster, make sure the version of the destination cluster is not earlier than the current cluster. Select or deselect Overwrite same-name indexes in the destination cluster. Data restoration using snapshots works by overwriting existing snapshot files. When there are same-name indexes in the destination cluster, you need to select this option in order to restore same-name, same-shard structure indexes. Indexes with a different shard structure cannot be restored. Exercise caution when performing this operation.

7. Click OK to get started. If restoration succeeds, Task Status of the snapshot in the snapshot list will change to Restoration succeeded, and the index data is re-generated based on the snapshot.