Recovering from local metadata store failure or corruption

If the local metadata store fails, perform the following steps on the affected DataNode:

1. Put the DataNode in maintenance mode.

2. Stop the HDFS DataNode software.

3. Shut down Data Optimizer.

4. Choose one of the following actions:

   • If the metadata store is corrupted, delete all metadata store files (metadata.db3*) stored in the folder identified by the CACHE_DIR or MD_STORE_DIR (if present) configuration parameter.

   • If the drive hosting the folder identified by the CACHE_DIR or MD_STORE_DIR (if present) configuration parameter has failed, then change the parameter to point to a folder on a healthy drive.

5. Edit the Data Optimizer configuration file for the DataNode and add or edit the property RECOVERY_MODE, to set the value to true.

6. Restart Data Optimizer.

7. Restart the HDFS DataNode software.

8. Take the HDFS DataNode out of maintenance mode.

After completing the these steps, the Data Optimizer software runs in a passive, opportunistic recovery mode and is fully functional. As file system operations are performed, Data Optimizer rebuilds its local metadata store opportunistically.

Note: Passive recovery does not fully restore the local metadata store to an authoritative state; active recovery is required for that purpose.