[PVE-User] LVM question

[Leandro Roggerone <leandro@tecnetmza.com.ar>]

Hi guys , after install a new storage to my box , had to create lvm-thin.
Im not very good with lvm , after reading some docs , and links like:
https://forum.proxmox.com/threads/how-to-create-an-lvm-thinpool-and-vz-directory-on-the-same-disk.62901/

I got a working solution  but have also some questions about it.
This is what I did:

 wipefs -a /dev/sdb

sgdisk -N 1 /dev/sdb

pvcreate --metadatasize 1024M -y -ff /dev/sdb1

vgcreate --metadatasize 1024M proxvg /dev/sdb1

lvcreate -l 100%FREE --poolmetadatasize 1024M --chunksize 256 -T -n
proxthin proxvg

lvcreate -n proxvz -V 1.1T proxvg/proxthin

mkfs.ext4 /dev/proxvg/proxvz

mkdir /media/vz

echo '/dev/proxvg/proxvz /media/vz ext4 defaults,errors=remount-ro 0 2' >>
/etc/fstab

mount -a


And have following result:


root@pve2:~# lvs
  LV            VG     Attr       LSize    Pool     Origin Data%  Meta%
 Move Log Cpy%Sync Convert
  proxthin      proxvg twi-aotz--    1.63t                 22.03  6.34

  proxvz        proxvg Vwi-aotz--    1.10t proxthin        1.67
root@pve2:~# lvdisplay
  --- Logical volume ---
  LV Name                proxthin
  VG Name                proxvg
  LV UUID                4cEIr9-3ZVQ-vsy1-q9ZX-GsaD-7oq0-pZixsX
  LV Write Access        read/write
  LV Creation host, time pve2, 2021-04-01 13:09:41 -0300
  LV Pool metadata       proxthin_tmeta
  LV Pool data           proxthin_tdata
  LV Status              available
  # open                 3
  LV Size                1.63 TiB
  Allocated pool data    22.03%
  Allocated metadata     6.34%
  Current LE             428451
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:2

  --- Logical volume ---
  LV Path                /dev/proxvg/proxvz
  LV Name                proxvz
  VG Name                proxvg
  LV UUID                huzpPT-g0Gd-3Jwb-2ydz-InHh-73vN-Jnc5TR
  LV Write Access        read/write
  LV Creation host, time pve2, 2021-04-01 13:10:12 -0300
  LV Pool name           proxthin
  LV Status              available
  # open                 1
  LV Size                1.10 TiB
  Mapped size            1.67%
  Current LE             288359
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:4


Have following comments:

I can create VMs on proxthin partition so it is ok.

I can create backup on  proxvz partition so it is ok.

What im concerned about is:

Physic storage space is about 1.8TG , how is it possible to create a 1.6
and 1.1T volumnes inside ?
It can be a problem in the future ?
I was thinking about reduce proxthin partition to 600Gb aprox , so it make
same sense 1.1T + 600G aprox 1.8 T
But there is no LV Path on proxthin partition so I can unmount and the
reduce.
So ..
What im missing here ? do I need to reduce proxthin partition ( I do need
the 1.1T partition to backup).
Hope to be clear about this guys.
Any comment would be wellcome.
Leandro.