Before I upgrade our Nautilus ceph to Octopus, I would like to make sure I am able to replace existing OSDs when they fail.  However, I have not been able to create an OSD in Octopus with the layout we are using in Nautilus.  I am testing this on a VM cluster so as not to touch any production systems. Our existing servers partition one SSD as block_db for 4 HDD OSDs. ie:     OST.0   block: /dev/sda,   block.db:  /dev/sdn1     OST.1   block: /dev/sdb,   block.db:  /dev/sdn2     OST.2   block: /dev/sdc,   block.db:  /dev/sdn3     OST.3   block: /dev/sdd,   block.db:  /dev/sdn4 etc. My understanding is that I will need to apply an advanced osd service to achieve this layout.  As each server is is similar the above, I could create 4 services (osd.disk0 - osd.disk3) and apply it to each host.  I tried something similar to this: service_type: osd service_id: disk0 placement:   host_pattern: 'storage*' data_devices:   paths:     - /dev/sda db_devices:    paths:      - /dev/sdn1 But the yaml was rejected with "Exception: Failed to validate Drive Group: `paths` is only allowed for data_devices", although it appears to be valid in the data structures here:     https://docs.ceph.com/en/latest/cephadm/osd/#deploy-osds https://people.redhat.com/bhubbard/nature/default/mgr/orchestrator_modules/ I tried to use a combination of size and db_slots for the db_device, but I could not get the OSD to put the block.db on the separate device.   Is this possible using the advanced placement method to orchestration, or should I just focus on using "cephadm ceph-volume" to create the OSDs in the desired layout? NOTE:  I am trying to avoid installing ceph directly on the host OS (to use ceph-volume) as I do like the containerized approach in octopus. Thank you, Gary -- Gary Molenkamp Computer Science/Science Technology Services Systems Administrator University of Western Ontario molenkam(a)uwo.ca http://www.csd.uwo.ca (519) 661-2111 x86882 (519) 661-3566