ceph-volume lvm list is O(n^2)
ceph-volume lvm list calls
/sbin/lvs --noheadings --readonly --separator=";" -o lv_tags,lv_path,lv_name,vg_name,lv_uuid,lv_size once for each disk,
lvs iterates over all the disk causing a total of
n^2 disk accesses.
This is especially annoying if you have (partially) broken disks or if your disks are currently overloaded. I've seen this command take several minutes on some systems with only 24 disks under heavy IO load.