hi, cephers I want to upgrade my ceph cluster from firefly(0.80.11) to hammer, when i successfully install hammer deb package on all my hosts, then i update monitor first, and it success. but when i restart osds on one host to upgrade, it failed, osds cannot startup, then i want to downgrade to firefly again to keep my cluster going on, after i reinstall firefly deb package, i failed to start osds on the host, here is the log: 2016-03-07 09:47:14.704242 7f2f11ba87c0 0 ceph version 0.80.11 (8424145d49264624a3b0a204aedb127835161070), process ceph-osd, pid 37459 2016-03-07 09:47:14.709159 7f2f11ba87c0 -1 filestore(/var/lib/ceph/osd/ceph-0) FileStore::mount : stale version stamp 4. Please run the FileStore update script before starting the OSD, or set filestore_update_to to 3 2016-03-07 09:47:14.709176 7f2f11ba87c0 -1 ** ERROR: error converting store /var/lib/ceph/osd/ceph-0: (22) Invalid argument 2016-03-07 09:47:18.385399 7f98478187c0 0 ceph version 0.80.11 (8424145d49264624a3b0a204aedb127835161070), process ceph-osd, pid 39041 2016-03-07 09:47:18.390320 7f98478187c0 -1 filestore(/var/lib/ceph/osd/ceph-0) FileStore::mount : stale version stamp 4. Please run the FileStore update script before starting the OSD, or set filestore_update_to to 3 2016-03-07 09:47:18.390337 7f98478187c0 -1 ** ERROR: error converting store /var/lib/ceph/osd/ceph-0: (22) Invalid argument how can i downgrade to firefly successfully? _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com