Here are the most useful Ceph commands that every Ceph administrator should know — grouped by purpose and explained with context and screenshots, especially when working with Proxmox VE.

Cluster Health and Status

1. ceph -s

Shows overall cluster health summary.

ceph -s

Output includes:

• Health status (HEALTH_OK / WARN / ERR)
• Number of OSDs, MONs, MGRs
• I/O rates
• PG state

2. ceph health detail

Gives detailed information about any health warnings.

ceph health detail

3. ceph df

Shows disk usage by pools and objects.

ceph df

4. ceph status

Same as ceph -s, but more verbose output in some versions.

OSDs (Object Storage Daemons)

5. ceph osd tree

Displays the hierarchical layout of OSDs (nodes, devices).

ceph osd tree

6. ceph osd status

Gives the up/in status of all OSDs.

7. ceph osd df

Detailed OSD usage report (space, performance weight).

8. ceph osd pool ls

Lists all storage pools.

9. ceph osd pool stats

Stats per pool — useful for performance monitoring.

10. ceph osd out <osd-id>

Mark an OSD out (for maintenance or replacement).

ceph osd out osd.3

11. ceph osd in <osd-id>

Bring an OSD back in to the cluster.

ceph osd in osd.3

12. ceph osd crush reweight <osd-id> <weight>

Manually adjust an OSD’s relative data weight.

ceph osd crush reweight osd.2 0.8

MONs and MGRs

13. ceph quorum_status

Shows the current monitor quorum — useful for troubleshooting MON issues.

14. ceph mgr dump

Displays manager daemon status and modules.

PGs (Placement Groups)

15. ceph pg stat

Summary of PG states (active+clean, degraded, etc.).

16. ceph pg dump

Detailed info about all placement groups (very verbose).

17. ceph pg ls-by-pool <pool-name>

List PGs belonging to a specific pool.

Pools and Images

18. rbd ls -p <pool>

List RBD images in a pool.

rbd ls -p vm-storage

19. rbd info <image>

Show details of a block image.

rbd info -p vm-storage vm-100-disk-0

20. rbd snap ls <image>

List all snapshots for a given image.

21. rbd resize <image> --size <MB>

Resize an image (expand).

rbd resize vm-100-disk-0 --size 20480

Maintenance & Troubleshooting

22. ceph tell osd.* bench

Benchmark all OSDs.

23. ceph osd scrub <osd-id>

Manually trigger a scrub on an OSD (data consistency check).

24. ceph balancer status

Check if automatic balancing is active.

25. ceph mgr module enable <module>

Enable optional modules like dashboard, prometheus, etc.

ceph mgr module enable dashboard

Authentication

26. ceph auth list

List all Ceph auth keys.

27. ceph auth get <client>

Get a specific auth key.

ceph auth get client.admin

28. ceph auth del <client>

Remove a client key.

Cleaning Up

29. ceph osd purge <osd-id> --yes-i-really-mean-it

Completely remove an OSD.

30. ceph mon remove <mon-id>

Remove a monitor (if removed physically or decommissioned).

Proxmox Specific

If you’re managing Ceph from within Proxmox VE, some tasks are best handled using:

pveceph status
pveceph pool ls
pveceph osd create <disk>
pveceph install --version <nautilus|octopus|quincy>

These integrate with Proxmox-specific configurations and help maintain UI synchronization.

Get in touch with Saturn ME today for a free Ceph consulting session—no strings attached.