The rados command‑line utility is the primary way to interact directly with a Ceph Object Storage cluster. It lets you list pools, put and get objects, create and manage snapshots, and perform other low‑level operations. Below is a practical, step‑by‑step guide for common tasks.

Prerequisites

1. Ceph client configuration – Ensure you have a working ceph.conf and a keyring that grants the required capabilities (e.g., client.admin or a custom client with osd, mon, mgr caps).
2. Ceph CLI installed – On a workstation or admin node, install the Ceph packages (ceph-common, ceph-mgr, etc.) that provide the rados binary.
3. Authentication – Verify you can run a simple rados -i client.admin command without error.

Basic Commands

1. List available pools

rados lspools

Shows all pools defined in the cluster.

2. Show pool details (including size, usage, etc.)

rados df

Provides a summary of storage utilisation per pool.

3. List objects in a pool

rados -p  ls

Replace with the actual pool name. This displays object IDs and their sizes.

4. Upload (put) an object

rados -p  put  

Example:

rados -p photos put vacation.jpg /home/user/Pictures/vacation.jpg

5. Download (get) an object

rados -p  get  

Example:

rados -p photos get vacation.jpg /tmp/vacation_download.jpg

6. Delete an object

rados -p  rm 

7. List snapshots of a pool

rados snap ls 

Shows all snapshot names for the specified pool.

8. Create a snapshot

rados snap create  

Example:

rados snap create photos snap_2023_09_15

9. Roll back to a snapshot

rados snap rollback  

Reverts the pool’s state to the chosen snapshot.

10. Remove a snapshot

rados snap rm  

Advanced Usage

Using a non‑admin client

If you have created a dedicated client (e.g., client.radosgw for RGW access), specify the client name and keyring:

rados -c /etc/ceph/ceph.conf -n client.radosgw -p  ls

Bulk operations

You can combine rados with shell loops for batch processing. Example: copy all objects from one pool to another:

for obj in $(rados -p source_pool ls); do
    rados -p target_pool cp $obj $obj
done

Monitoring long‑running operations

Add --pool to limit output, or use --format json for script‑friendly parsing:

rados -p photos ls --format json

Common Troubleshooting Tips

• Permission denied – Verify the client’s keyring has osd and mon caps. Use ceph auth export client. to export a working keyring.
• Pool not found – Ensure the pool exists (rados lspools) and that you are targeting the correct cluster endpoint.
• Network issues – Test connectivity to the monitor(s) with ceph -s. If monitors are unreachable, check DNS or firewall settings.
• Large object lists – When dealing with many objects, pipe the output to head or tail to avoid overwhelming the terminal.

Where to Find More Information

• The official Ceph documentation for rados is available at https://docs.ceph.com/en/latest/rbd/rados-commands/.
• For cluster‑wide health checks, run ceph health status and ceph osd tree.

By following these steps you can efficiently manage objects, pools, and snapshots using the rados utility within a Ceph storage environment.