4. Create OSDs in ceph-volume's lvm mode¶

Date: 2026-10-16

Status¶

Accepted

Context¶

ceph-volume can prepare an OSD in raw mode, which writes BlueStore directly to the device, or in lvm mode, which writes it to a logical volume tagged with the OSD's metadata. In both modes, activation rebuilds the OSD's data directory from the device.

We plan to add an Intel Optane to hold BlueStore's database and write-ahead log for existing OSDs. In lvm mode, ceph-volume lvm new-db and ceph-volume lvm migrate attach and move them onto a logical volume, and the change is recorded in the OSD's tags. ceph-volume has no equivalent for raw OSDs, so the move would have to be done with ceph-bluestore-tool, and the new device added to the OSD's activation command by hand.

Decision¶

We'll create OSDs in ceph-volume's lvm mode.

Consequences¶

We'll move OSD databases to the Optane by hand with ceph-volume lvm new-db and ceph-volume lvm migrate, so the repo won't record where each database lives.