Chvilku si mi dal nadej, ale bohuzial.

root@pve1:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 3.7T 0 disk
├─sda1 8:1 0 1M 0 part
├─sda2 8:2 0 256M 0 part
└─sda3 8:3 0 3.7T 0 part
├─pve-swap 253:0 0 8G 0 lvm [SWAP]
├─pve-root 253:1 0 96G 0 lvm /
├─pve-data_tmeta 253:2 0 112M 0 lvm
│ └─pve-data 253:4 0 3.5T 0 lvm /var/lib/vz
└─pve-data_tdata 253:3 0 3.5T 0 lvm
└─pve-data 253:4 0 3.5T 0 lvm /var/lib/vz
sr0 11:0 1 1024M 0 rom
root@pve1:~# fstrim -v /var/lib/vz
/var/lib/vz: 3.4 TiB (3678652039168 bytes) trimmed
root@pve1:~# lvresize -L -2500G /dev/pve/data
File descriptor 7 (pipe:[15289952]) leaked on lvresize invocation. Parent PID 92067: bash
Thin pool volumes pve/data_tdata cannot be reduced in size yet.