Ah, I finally fond something that looks like an error message : 2014-07-02 11:07:57.817269 7f0692e3a700 7 mon.a at 0(leader).osd e1147 preprocess_boot from osd.3 10.192.2.70:6807/9702 clashes with existing osd: different fsid (ours: e44c914a-23e9-4756-9713-166de401dec6 ; theirs: c1cfff2f-4f2e-4c1d-a947-24bbc6f122ca) Not really sure how to fix it though. Cheers, Sylvain