Ceph » ceph-volume

The is_device function in ceph-volume/util/disk.py is supposed to return false for partitions. This is later used to not create LVMs in the prepare command, see https://docs.ceph.com/en/quincy/ceph-volume/lvm/prepare/#ceph-volume-lvm-prepare:

For both block.db and block.wal, partitions can be used as-is, and therefore are not made into logical volumes.

This behavior changed with this commit: https://github.com/ceph/ceph/commit/5705e10e809cdc9f70018263c54a63ac4a02809c
Without lsblk, the stats fallback is used for partitions, and that happens to not work. So the bug was kind of hidden until this commit.

It's easy to test, you can copy the is_device and _stat_is_device and test them locally, they return true for my partitions. ceph-volume prepare therefore makes logical volumes on top of the partitions.