How to store backups on same physical disk, but NOT on root partition - maybe its own LV?

[teeeeee]

I have a 128 GB internal SSD disk on my machine, and have installed a fresh Proxmox with the following setup:

• 16 GiB for the Proxmox OS root (set using the maxroot parameter during installation)
• 7.58 GiB allocated to SWAP
• 32 GiB allocated to VM-100

It seems that the proxmox installer has already created an LVM-Thin section, allocating almost all of the remaining space of size 83.65 GB (88% "assigned to LVs"). Not sure why.

Immediately after creating the 32 GiB VM, then 5.26 GB of space is used in LVM-Thin.

After doing a backup of VM-100 to "local", I can see that the size of the backup file is 1.5 GB (the total disk usage of the 16 GB root partition has increased from 3.6GB to 5.1GB). This backup is currently stored on the root partition at /var/lib/vz/dump.

I would like to keep the storage of the backups separate from the 16 GB root partition (but still on the same physical disk), thus keeping the 16 GB partition for the Proxmox OS only. This is because I don't like the idea of the root partition getting full if backups increase. Ideally, I would like to keep my 16 GB for the root, with maybe another 16 GB for backups, and the rest for VM disks. Would it make sense to carve out some new storage from the 83.65 GB LVM-Thin, and use this for backups? If so, how do you do this?

Note:

• I am not concerned that my backups are on the same internal disk as the OS (I plan to copy the backups periodically to a connected external drive as well, for redundancy, but want a copy on the internal disk in case the external one fails)
• I am not concerned about storage of ISO files (I plan to delete them immediately after use, and not store them)

Some outputs with disk information:

root@proxmox:~# pvs
  PV         VG  Fmt  Attr PSize    PFree
  /dev/sda3  pve lvm2 a--  <118.24g 14.75g
root@proxmox:~# vgs
  VG  #PV #LV #SN Attr   VSize    VFree
  pve   1   5   0 wz--n- <118.24g 14.75g
root@proxmox:~# lvs
  LV            VG  Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  data          pve twi-aotz-- 77.90g             4.98   1.70                           
  root          pve -wi-ao---- 16.00g                                                   
  swap          pve -wi-ao----  7.58g                                                   
  vm-100-disk-0 pve Vwi-aotz--  4.00m data        0.00                                   
  vm-100-disk-1 pve Vwi-aotz-- 32.00g data        12.13

root@proxmox:~# df -h
Filesystem            Size  Used Avail Use% Mounted on
udev                  3.8G     0  3.8G   0% /dev
tmpfs                 777M  948K  776M   1% /run
/dev/mapper/pve-root   16G  3.7G   12G  25% /
tmpfs                 3.8G   34M  3.8G   1% /dev/shm
tmpfs                 5.0M     0  5.0M   0% /run/lock
efivarfs              128K   73K   51K  60% /sys/firmware/efi/efivars
/dev/fuse             128M   16K  128M   1% /etc/pve
tmpfs                 777M     0  777M   0% /run/user/0

root@proxmox:~# fdisk -l
Disk /dev/sda: 119.24 GiB, 128035676160 bytes, 250069680 sectors
Disk model: TOSHIBA THNSNF12
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: A6B9BBB2-89EF-4F40-B901-9B2B5ACF66E3

Device       Start       End   Sectors   Size Type
/dev/sda1       34      2047      2014  1007K BIOS boot
/dev/sda2     2048   2099199   2097152     1G EFI System
/dev/sda3  2099200 250069646 247970447 118.2G Linux LVM


Disk /dev/mapper/pve-swap: 7.58 GiB, 8141144064 bytes, 15900672 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/pve-root: 16 GiB, 17179869184 bytes, 33554432 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/pve-vm--100--disk--0: 4 MiB, 4194304 bytes, 8192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 65536 bytes / 65536 bytes


Disk /dev/mapper/pve-vm--100--disk--1: 32 GiB, 34359738368 bytes, 67108864 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 65536 bytes / 65536 bytes
Disklabel type: gpt
Disk identifier: 24F2D7C1-CFAC-4E79-B9E4-4F3FDEADD112

Device                                   Start      End  Sectors  Size Type
/dev/mapper/pve-vm--100--disk--1-part1    2048    67583    65536   32M EFI System
/dev/mapper/pve-vm--100--disk--1-part2   67584   116735    49152   24M Linux filesystem
/dev/mapper/pve-vm--100--disk--1-part3  116736   641023   524288  256M Linux filesystem
/dev/mapper/pve-vm--100--disk--1-part4  641024   690175    49152   24M Linux filesystem
/dev/mapper/pve-vm--100--disk--1-part5  690176  1214463   524288  256M Linux filesystem
/dev/mapper/pve-vm--100--disk--1-part6 1214464  1230847    16384    8M Linux filesystem
/dev/mapper/pve-vm--100--disk--1-part7 1230848  1427455   196608   96M Linux filesystem
/dev/mapper/pve-vm--100--disk--1-part8 1427456 67108830 65681375 31.3G Linux filesystem