Another method to dynamically change a Ceph configuration

In a previous post, we saw how to dynamically change a tunable on a running Ceph cluster dynamically. Unfortunately, such a change is not permanent, and will revert back to the previous setting once ceph is restarted.

Rather than using the command 'ceph tell', I recently came upon another way to change configuration values.

We'll try changing the tunable 'mon_osd_full_ratio' once again.

1. Get the current setting

# ceph daemon osd.1 config get mon_osd_full_ratio { "mon_osd_full_ratio": "0.75"}

2. Change the configuration value using 'ceph daemon'.

# ceph daemon osd.1 config set mon_osd_full_ratio 0.85 { "success": "mon_osd_full_ratio = '0.85' "}

3. Check if the change has been introduced.

# ceph daemon osd.1 config get mon_osd_full_ratio { "mon_osd_full_ratio": "0.85"}

4. Restart the 'ceph' service

# service ceph restart

5. Check the status

# ceph daemon osd.1 config get mon_osd_full_ratio { "mon_osd_full_ratio": "0.75"}

NOTE: Please note that the changes introduced with 'ceph tell' as well as 'ceph daemon' is not persistent across process restarts.