Reclaim Space from Ceph for LVM

Intended when Ceph uses an entire disk for an OSD.

Useful for homelab SFF PCs running Proxmox.

Show the current setup of the block device

lsblk
ceph osd tree

Migrate data from a Ceph OSD

ceph osd out osd.1

Check if an OSD can be removed, then destroyed

while ! ceph osd safe-to-destroy osd.1 ; do sleep 10 ; done

Stop the local service – this also marks the OSD as down

systemctl stop ceph-osd@1.service

Destroy the OSD – keeps the ID reserved so it can be reused later

ceph osd destroy 1 --yes-i-really-mean-it

Remove the Ceph volume

lvremove pve/ceph

Create a Proxmox Data LVM-thin volume, size to 200G

lvcreate --size 200G --thin --name data pve

Create a Ceph volume, using the remaining space

lvcreate --extents 100%FREE --name ceph pve

Get a Ceph Key

ceph auth get client.bootstrap-osd > /var/lib/ceph/bootstrap-osd/ceph.keyring

Put Ceph onto the LV

ceph-volume lvm create --osd-id 1 --data pve/ceph