I was install openstack rdo all in one, i was set lvm thin and over_subscription_ratio to 20. but why, when i lunch instance with disk 20g for example, disk capacity is reduced by 20g directly..? i think it is still thick provisioning, is any need more configuration??

thank you.

my configuration:

[root@centos-thin ~(keystone_admin)]# pvs
  PV         VG             Fmt  Attr PSize   PFree
  /dev/loop0 cinder-volumes lvm2 a--   20.60g 1012.00m
  /dev/sda2  cl_centos-thin lvm2 a--  199.00g   15.82g
[root@centos-thin ~(keystone_admin)]# vgs
  VG             #PV #LV #SN Attr   VSize   VFree
  cinder-volumes   1   1   0 wz--n-  20.60g 1012.00m
  cl_centos-thin   1   3   0 wz--n- 199.00g   15.82g
[root@centos-thin ~(keystone_admin)]# lvs
  LV                  VG             Attr       LSize   Pool   Origin Data%  Meta%  Move Log Cpy%Sync Convert
  cinder-volumes-pool cinder-volumes twi-a-tz--  19.57g               0.00   0.55
  pool00              cl_centos-thin twi-aotz-- 183.00g               2.96   1.89
  root                cl_centos-thin Vwi-aotz-- 175.12g pool00        3.09
  swap                cl_centos-thin Vwi-aotz--   7.88g pool00        0.00
[root@centos-thin ~(keystone_admin)]#

[root@centos-thin ~(keystone_admin)]# egrep -i "lvm_type|max_over_subscription_ratio" /etc/cinder/cinder.conf | grep -v "#"
max_over_subscription_ratio = 20.0
lvm_type = thin
[root@centos-thin ~(keystone_admin)]#
[root@centos-thin ~(keystone_admin)]# tail /etc/cinder/cinder.conf
#ciphers = <None>

[lvm]
volume_backend_name=lvm
volume_driver=cinder.volume.drivers.lvm.LVMVolumeDriver
iscsi_ip_address=192.168.10.223
iscsi_helper=lioadm
volumes_dir=/var/lib/cinder/volumes
lvm_type = thin
max_over_subscription_ratio = 20.0
[root@centos-thin ~(keystone_admin)]#

Thank you,