Summary

In this chapter, you learned how to troubleshoot Ceph when all looks lost. If Ceph is unable to recover PGs itself, you now understand how to manually rebuild PGs from failed OSDs. You can also rebuild the monitor's database if you lose all of your monitor nodes but still have access to your OSDs. You explored the process of recreating RBDs from the raw data remaining on your OSDs. Finally, you configured two separate Ceph clusters and configured replication between them using RBD mirroring to provide a failover option, should you encounter a complete Ceph cluster failure.