Holger, Eugen, thanks! I tried the ceph-volume approach, and it worked. The only strange thing was that "ceph osd metadata $ID | grep devices" reports "bluefs_db_devices": "nvme1n1", while in fact the db+wal LV/PV/VG is on a _partition_ of that device, nvme1n1p4. Another problem is how to remove the volume group on that device. I expected "ceph-volume zap /dev/nvme1n1p4" to be able to do it, but it failed with: stderr: wipefs: error: /dev/nvme1n1p4: probing initialization failed: Device or resource busy --> failed to wipefs device, will try again to workaround probable race condition In the end I did osd# vgchange -a n ceph-1cbc1f4d-9043-4a10-844b-c7fe28b4a333 osd# vgremove ceph-1cbc1f4d-9043-4a10-844b-c7fe28b4a333 which worked. Can ceph-volume zap be used for this as well? FWIW, all the commands I did: mon# ceph osd metadata 8 | grep devices "bluefs_db_devices": "nvme1n1", "bluestore_bdev_devices": "sda", "devices": "nvme1n1,sda", "objectstore_numa_unknown_devices": "sda", mon# ceph osd set noout osd# ls -l /var/lib/ceph/osd/ceph-8 lrwxrwxrwx. 1 ceph ceph 93 Feb 3 22:11 block -> /dev/ceph-179dc46e-f620-4b54-b663-24e5be779b3b/osd-block-d38e32da-fc81-4744-ad3a-750ba2cf3bc6 lrwxrwxrwx. 1 ceph ceph 90 Feb 3 22:11 block.db -> /dev/ceph-1cbc1f4d-9043-4a10-844b-c7fe28b4a333/osd-db-ce2a1653-3cf3-4eac-b74c-3d49bb4ef170 osd# systemctl stop ceph-osd@8.service osd# ceph-volume lvm migrate --osd-id 8 --osd-fsid d38e32da-fc81-4744-ad3a-750 osd# ba2cf3bc6 --from db wal --target ceph-179dc46e-f620-4b54-b663-24e5be779b3b/osd-block-d38e32da-fc81-4744-ad3a-750ba2cf3bc6 osd# vgchange -a n ceph-1cbc1f4d-9043-4a10-844b-c7fe28b4a333 osd# vgremove ceph-1cbc1f4d-9043-4a10-844b-c7fe28b4a333 osd# systemctl start ceph-osd@8.service mon# ceph osd unset noout mon# watch ceph -s # till it reports HEALTH_OK Thanks, -Yenya -- | Jan "Yenya" Kasprzak <kas at {fi.muni.cz - work | yenya.net - private}> | | https://www.fi.muni.cz/~kas/ GPG: 4096R/A45477D5 | We all agree on the necessity of compromise. We just can't agree on when it's necessary to compromise. --Larry Wall