Hey all ,

So when I was setting up OpenStack I used packstack but left the default 20GB cinder-volumes size. It's coming back to bite me in the ass since I can basically only have 2 10GB VMs before it stops me creating more.

overall filesystem

[root@openstack ~]# df -h
Filesystem                         Size  Used Avail Use% Mounted on
/dev/mapper/centos_openstack-root   50G  9.6G   41G  20% /
devtmpfs                           126G     0  126G   0% /dev
tmpfs                              126G  4.0K  126G   1% /dev/shm
tmpfs                              126G  146M  126G   1% /run
tmpfs                              126G     0  126G   0% /sys/fs/cgroup
/dev/nvme0n1p2                     497M  165M  332M  34% /boot
/dev/nvme0n1p1                     200M  9.5M  191M   5% /boot/efi
/dev/loop0                         1.9G  6.1M  1.7G   1% /srv/node/swiftloopback
tmpfs                               26G     0   26G   0% /run/user/0
/dev/mapper/centos_openstack-home  5.5T   33M  5.5T   1% /home

Logical and physical volumes

[root@openstack ~]# pvs
  PV             VG               Fmt  Attr PSize  PFree  
  /dev/loop1     cinder-volumes   lvm2 a--  20.60g 612.00m
  /dev/nvme0n1p3 centos_openstack lvm2 a--   1.82t  60.00m
  /dev/nvme1n1p1 centos_openstack lvm2 a--   1.82t      0 
  /dev/nvme2n1p1 centos_openstack lvm2 a--   1.82t      0 
[root@openstack ~]# lvs
  LV                                          VG               Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  home                                        centos_openstack -wi-ao----  5.40t                                                    
  root                                        centos_openstack -wi-ao---- 50.00g                                                    
  swap                                        centos_openstack -wi-ao----  4.00g                                                    
  volume-1c95b499-b084-4ea0-959e-7be4f2f559d8 cinder-volumes   -wi-ao---- 10.00g                                                    
  volume-57dab2d5-b65b-4f20-bcf3-8e5213442fb8 cinder-volumes   -wi-ao---- 10.00g                                                    
[root@openstack ~]# vgs
  VG               #PV #LV #SN Attr   VSize  VFree  
  centos_openstack   3   3   0 wz--n-  5.46t  60.00m
  cinder-volumes     1   2   0 wz--n- 20.60g 612.00m

So my goal was to reduce some of the size in centos_openstack and allow more to cinder-volumes so I can have more machines set up

Attempt 1

From looking at this previous question asked https://ask.openstack.org/en/question/53325/how-to-increase-volume-capacity/ (here)

However on following the advise I was warned

the guide told you to partition the loopback device. In this step, they overwrite the partition table and make the loopback device itself an LVM PV. I'm only bothering to point this out because it illustrates that the author of that guide is giving you dangerous advice because he doesn't understand what he's doing.

Anyway following the steps even with the warning after a system reboot I got this

[root@openstack ~(keystone_admin)]# pvs
  WARNING: Device for PV XwMJfT-bpgu-f2fi-S1qR-ECQN-n3VS-JJU6xt not found or rejected by a filter.
  PV             VG               Fmt  Attr PSize  PFree 
  /dev/loop1     cinder-volumes   lvm2 a--  20.60g 10.60g
  /dev/nvme0n1p3 centos_openstack lvm2 a--   1.82t 60.00m
  /dev/nvme1n1p1 centos_openstack lvm2 a--   1.82t     0 
  /dev/nvme2n1p1 centos_openstack lvm2 a--   1.82t     0 
  [unknown]      cinder-volumes   lvm2 a-m   4.88t  4.88t
[root@openstack ~(keystone_admin)]# vgs
  WARNING: Device for PV XwMJfT-bpgu-f2fi-S1qR-ECQN-n3VS-JJU6xt not found or rejected by a filter.
  VG               #PV #LV #SN Attr   VSize VFree 
  centos_openstack   3   3   0 wz--n- 5.46t 60.00m
  cinder-volumes     2   1   0 wz-pn- 4.90t  4.89t

Attempt 2

So trying a different approach

[root@openstack ~]# losetup -l
NAME       SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE ...