Create Bluestore OSD backed by SSD

Dont take my word for it on the WAL sizing – Check http://docs.ceph.com/docs/mimic/rados/configuration/bluestore-config-ref/

This script will create a spare 20G Logical volume to use as the WAL for a second spinner later if you need it

export SSD=sdc
export SPINNER=sda

vgcreate ceph-ssd-0 /dev/$SSD
vgcreate ceph-hdd-0 /dev/$SPINNER

lvcreate --size 20G -n block-0 ceph-hdd-0
lvcreate -l 100%FREE -n block-1 ceph-hdd-0

lvcreate --size 20G -n ssd-0 ceph-ssd-0
lvcreate --size 20G -n ssd-1 ceph-ssd-0
lvcreate -l 100%FREE -n ssd-2 ceph-ssd-0

ceph-volume lvm create --bluestore --data ceph-hdd-0/block-1 --block.db ceph-ssd-0/ssd-0
ceph-volume lvm create --bluestore --data ceph-ssd-0/ssd-2