Huge backup file of VM

[dussyaka]

Hello there.

pveversion
pve-manager/8.1.3/b46aac3b42da5d15 (running kernel: 6.2.16-10-pve)

I've got a VM with a 96Gb disk.

  qm config 100
boot: order=ide2;sata0;net0
cores: 3
cpu: x86-64-v2-AES
ide2: none,media=cdrom
memory: 5120
meta: creation-qemu=8.0.2,ctime=1692278490
name: web
net0: virtio=32:0D:A0:90:A6:D1,bridge=vmbr1
numa: 0
onboot: 1
ostype: l26
sata0: local:100/vm-100-disk-0.qcow2,size=96G,ssd=1
scsihw: virtio-scsi-single
smbios1: uuid=12a0f08c-ddaf-4ca6-bc4e-cf23575fe0a8
sockets: 1
startup: order=4
vmgenid: d064b639-26b0-481f-86ee-ae9220cfafa5

df -h
udev                                2,4G            0  2,4G            0% /dev
tmpfs                               493M         2,0M  491M            1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv    93G          20G   69G           23% /
tmpfs                               2,5G         616K  2,5G            1% /dev/shm
tmpfs                               5,0M            0  5,0M            0% /run/lock
tmpfs                               2,5G            0  2,5G            0% /sys/fs/cgroup
/dev/sda2                           2,0G         209M  1,6G           12% /boot
/dev/loop0                           64M          64M     0          100% /snap/core20/2015
/dev/loop1                           41M          41M     0          100% /snap/snapd/20092
/dev/loop2                           41M          41M     0          100% /snap/snapd/20290
/dev/loop3                           92M          92M     0          100% /snap/lxd/24061
/dev/loop4                           64M          64M     0          100% /snap/core20/2105
tmpfs                               493M            0  493M            0% /run/user/1000

I think backup file of this VM should weigh 20-30Gb, but it is 75 Gb!
I read about fstim on the forum, and do this on VM and on PROXMOX machine, but nothing has changed.
Do you have any ideas about how to solve this problem? If I skipped thread on this forum about this, sorry!
Thank you very much!

 

[Chris]

Hi
according to your VM config, you have not enabled the discard option on the VM disk, see [0]. Further, I would recommend to use scsi over sata as bus for the disks, as this is generally better supported/tested. Note that you might have to move the disk in order to clean up already freed blocks, as from the VM perspective they probably are already freed.

Please also have a look at this thread [1], as the discussion there coveres a similar issue.

[0] https://pve.proxmox.com/pve-docs/pve-admin-guide.html#qm_hard_disk_discard
[1] https://forum.proxmox.com/threads/fstrim-and-backup-size.86975/

 

[dussyaka]

Yeap, 7Gb is better.
Steps I did:

• Turn on "Discard" option on Hardware -> Hard Disk -> Discard. (In Russian localization this is "Отклонить", that seems like "Reject". I thought this option disables the disk...);
• Turn off "SSD emulation".

Thank you.

 

[Chris]

Yeap, 7Gb is better.
Steps I did:

• Turn on "Discard" option on Hardware -> Hard Disk -> Discard. (In Russian localization this is "Отклонить", that seems like "Reject". I thought this option disables the disk...);
• Turn off "SSD emulation".

Thank you.

Glad this solved the issue for you.

Regarding the translation, maybe you have suggestions for improving that, we heavily depend on the community for translations and it is a good point to start contributing. If interested, the translations can be found here [0]. For possible patch submissions, please adhere to the developer documentation [1].

[0] https://git.proxmox.com/?p=proxmox-...106b88535937ea20914b6bc6;hb=refs/heads/master
[1] https://pve.proxmox.com/wiki/Developer_Documentation