When facing a situation where one placement group (PG) is inconsistent in a Ceph storage cluster, the following steps can be taken to investigate and address possible data damage:
Identify the affected PG: Determine the specific PG that is experiencing inconsistency by using Ceph CLI commands or monitoring tools like Ceph Dashboard.
Verify OSD status: Ensure that the Object Storage Daemons (OSDs) associated with the affected PG are running and in a healthy state. Use commands such as ceph osd tree and ceph osd status to gather OSD information.
Check Ceph logs: Examine the Ceph OSD and monitor logs for any error messages or warnings related to the affected PG. The logs can provide valuable insights into the nature of the inconsistency and potential causes.
Initiate data scrubbing: Trigger a data scrubbing process on the affected PG using the ceph pg scrub <pg_id> command. Monitor the progress and check for any repair actions taken during the scrub.
Analyze PG status: Use the ceph pg <pg_id> query command to gather detailed information about the PG's status, including the number of acting OSDs, recovery state, and misplaced objects. This information helps understand the extent of the inconsistency and guides further troubleshooting.
Recover misplaced objects: If the PG contains misplaced objects, initiate a recovery process to relocate them to the correct OSDs. Use the ceph pg repair <pg_id> command to start the recovery.
Monitor recovery progress: Keep a close eye on the recovery process using commands like ceph pg <pg_id> query and ceph -w to identify any errors or issues. Recovery time can vary depending on the PG size and cluster workload.
Verify data consistency: Once the recovery process completes, verify the consistency of the data in the affected PG. Use Ceph's checksum mechanisms or application-level checks to ensure data integrity and consistency.
Find out the PG id with the command "ceph health detail", then excute the below command
ceph pg repair pg-ID