How do reduce/optimize backup sizes

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thimplicity

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Feb 4, 2022
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Hi everyone,
I am doing local backups via PBS, but I also create vzdump backups that I back up to OneDrive via restic. I have tried to optimize backup sizes with cleaning up docker, fstrim as well as activating "ssd" and "discard" for the respective VMs.

I have multiple VMs that confuse me:
  1. Server: 50GB disk with ubuntu and multiple docker images. According to "df -h" 23GB free out of 48GB. The vzdump backup size: 12 GB
  2. Server: 100GB disk with ubuntu and multiple docker images. According to "df -h" 41GB free out of 98GB. The vzdump backup size: 76 GB
  3. Server: 200GB disk with ubuntu and multiple docker images. According to "df -h" 189GB free out of 197GB. The vzdump backup size: 51 GB
Two questions:
  • Why is there such a big difference between free/used space and the backup size
  • What else can I try to reduce backup sizes?
Thanks!
 
You need to wipe the formerly used disk space as it is not zero'ed out yet. So that means an image backup will still see data there even though the files have been deleted. Added: fstrim should be able to do this, but I know the dd method works for me YMMV.

See https://knowledge.broadcom.com/external/article/340005/reclaiming-disk-space-from-thin-provisio.html

TLDR:
Windows (live.sysinternals.com)
sdelete64 c: -z
Linux (Replace /tmp with other folder if you have multiple partitions/volumes. Be very careful with dd.)
dd if=/dev/zero of=/tmp/zeroes && rm -f /tmp/zeroes
 
Last edited:
Can you check the log of vzdump?
It should tell you how many data was found and tell you something about the compress ratio.

Code: 
101: 2024-11-30 01:41:32 INFO: backup is sparse: 281.66 GiB (55%) total zero data
101: 2024-11-30 01:41:32 INFO: transferred 512.00 GiB in 2486 seconds (210.9 MiB/s)
101: 2024-11-30 01:41:33 INFO: archive file size: 203.33GB


Code: 
INFO: backup is sparse: 290.06 GiB (75%) total zero data
INFO: transferred 384.00 GiB in 965 seconds (407.5 MiB/s)
INFO: archive file size: 59.31GB

Code: 
100: 2024-11-30 01:14:53 INFO: backup is sparse: 636.55 GiB (84%) total zero data
100: 2024-11-30 01:14:53 INFO: transferred 750.00 GiB in 886 seconds (866.8 MiB/s)
100: 2024-11-30 01:14:54 INFO: archive file size: 89.61GB

Try a 'fstrim -a' on your guest.

On windows guest, the defrag tool has memory issues in combination with virtio.
You have to manually overwrite the discard granularity for your guest machine.* See article here:
https://www.alldiscoveries.com/how-...frag-on-windows-server-virtualized-with-qemu/



* in case the article will be removed:

cd /etc/pve/qemu-server/
vi <id>.conf
add the following line:
Code: 
args: -global scsi-hd.discard_granularity=2097152
 
Last edited:
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thimplicity said:
Hi everyone,
I am doing local backups via PBS, but I also create vzdump backups that I back up to OneDrive via restic. I have tried to optimize backup sizes with cleaning up docker, fstrim as well as activating "ssd" and "discard" for the respective VMs.

I have multiple VMs that confuse me:
  1. Server: 50GB disk with ubuntu and multiple docker images. According to "df -h" 23GB free out of 48GB. The vzdump backup size: 12 GB
  2. Server: 100GB disk with ubuntu and multiple docker images. According to "df -h" 41GB free out of 98GB. The vzdump backup size: 76 GB
  3. Server: 200GB disk with ubuntu and multiple docker images. According to "df -h" 189GB free out of 197GB. The vzdump backup size: 51 GB
Two questions:
  • Why is there such a big difference between free/used space and the backup size
  • What else can I try to reduce backup sizes?
Thanks!
Click to expand...
You mentionex you use restic to upload vzdump to onedrive. Did you realize thay de-duplication does not work? So if you did a backup of a vm 5gb today and added 100mb of data tomorrow and do another backup you will upload another 5.1GB tomorrow instead of just 100MB

I am asking cause I did some testing today and found out this problem with my strategy to use restic for off-site backups and I want to see if you have the same issue. A quick search lead me to this https://forum.restic.net/t/backup-vma-proxmox-with-restic/1864 which confirmed my findings
 
ArionWolf said:
You mentionex you use restic to upload vzdump to onedrive. Did you realize thay de-duplication does not work? So if you did a backup of a vm 5gb today and added 100mb of data tomorrow and do another backup you will upload another 5.1GB tomorrow instead of just 100MB

I am asking cause I did some testing today and found out this problem with my strategy to use restic for off-site backups and I want to see if you have the same issue. A quick search lead me to this https://forum.restic.net/t/backup-vma-proxmox-with-restic/1864 which confirmed my findings
Click to expand...
Looks like I am having the same issues - did you find a resolution?
 
thimplicity said:
Yes, I have that locally, but I still would like to have a cloud backup (obviously in another location)
Click to expand...
Yoz could use a vserver or pbs cloud provider like tuxis.nl or cloud-pbs.com. i use a cheap vserver at netcup with PBS for vms and restic with a hetzner storagebox for data
 
ArionWolf said:
I am just using rclone to copy the vzdump from pbs to the cloud. And pbs encrypts the data so I dont need to worry about that otherwise I would have used restic
Click to expand...
Do you actually use rclone on the PBS datastore or the vzdumps vma-Files made with ProxmoxVEs native backup function? rclone on vma-Files should be fine. Using rclone to sync the PBS datastore is not something I would recommend due to reports about broken datastores after a rclone sync:
Z

Thread 'Datastore synced with Rclone broken?'

I'm trying to set up a remote sync to a friend's RPI for my Proxmox Backup Server. I've been using this script that uses Rclone with an encrypted remote (Crypt) on a schedule:
Bash: 
#!/bin/bash

# A simple script to back up PBS to Crypt remote

_lock_file=/root/.tertiary_backup.lock

_schedule_time=1:30
_max_duration="7.5h"
_cutoff_mode="soft"

_datastore_dir_name=Primary_Backup
_datastore_dir_path=/mnt/datastore/$_datastore_dir_name
_config_dir=$_datastore_dir_path/host_backup

_remote_user=user
_remote_ip=tailscale-ip
_remote_port=22
_remote_name=Tertiary_Backup_Crypt...
S

Thread 'PBS appears not to write to disk'

Hello friends.

New user of Proxmox and PBS here. I'm evaluating it for use in a tech company that is starting to need virtualization of a few services. Right now I have a basic working config on a local server:

PVE - running 4 x VMs
PBS - also running as a VM inside PVE. Datastore is configured to point at a section of thin storage within PVE, not a dedicated disk (yet).

My short term aim is to sync the backups on PBS with a cloud storage provider using Rclone. I am having trouble reading the backup files off the disk inside PBS. The backup appears to go fine from PVE-PBS. I can...
 
Johannes S said:
Do you actually use rclone on the PBS datastore or the vzdumps vma-Files made with ProxmoxVEs native backup function? rclone on vma-Files should be fine. Using rclone to sync the PBS datastore is not something I would recommend due to reports about broken datastores after a rclone sync:
Z

Thread 'Datastore synced with Rclone broken?'

I'm trying to set up a remote sync to a friend's RPI for my Proxmox Backup Server. I've been using this script that uses Rclone with an encrypted remote (Crypt) on a schedule:
Bash: 
#!/bin/bash

# A simple script to back up PBS to Crypt remote

_lock_file=/root/.tertiary_backup.lock

_schedule_time=1:30
_max_duration="7.5h"
_cutoff_mode="soft"

_datastore_dir_name=Primary_Backup
_datastore_dir_path=/mnt/datastore/$_datastore_dir_name
_config_dir=$_datastore_dir_path/host_backup

_remote_user=user
_remote_ip=tailscale-ip
_remote_port=22
_remote_name=Tertiary_Backup_Crypt...
S

Thread 'PBS appears not to write to disk'

Hello friends.

New user of Proxmox and PBS here. I'm evaluating it for use in a tech company that is starting to need virtualization of a few services. Right now I have a basic working config on a local server:

PVE - running 4 x VMs
PBS - also running as a VM inside PVE. Datastore is configured to point at a section of thin storage within PVE, not a dedicated disk (yet).

My short term aim is to sync the backups on PBS with a cloud storage provider using Rclone. I am having trouble reading the backup files off the disk inside PBS. The backup appears to go fine from PVE-PBS. I can...
Click to expand...
i was uploading the datastore did a wuick restore of one of my vm's and it worked the example you sent seems that they were encrypting the data with rclone which I wasn't doing.

But I am not taking chances I do a copy of my PBS server to a local NAS. So now I will try to upload that to the cloud. And in the case of needing to restore I would restore PBS than restore the VMs from PBS. Thinking It's actual much simpler this way
 
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After more testing I did run into some issue with rclone backup of the datastore. The verify and gc tasks kept failing and I was not able to perform a backup of one VMs due to one of the temp files or folder being missing in the .chunks folder. I couldn't figure our a solution so I restored pbs and decide to give restic a try to backuo the datastore.

Did 5 or so different tests with restic, backing up and restoring the backup, destroying pbs and recreating the datastore tried cutting the connection mid way through the backup process and continued afterwards and upon restoring verify and garbe collectiondworked and was able to restore vms and backup vms as if nothing happened. The plus side of restic is that it keeps permissions not need to do chown -R as in the case of rclone. Plus I have been using restic for some time noe and I feel comfortablr using it.

I'll keep testing over the coming months with more data and report back. But if it works I will be very happy cause restic is amazing and it was my initial plan to backup proxmox but since it cannot dedupe vzdumps I must use pbs as an intermediate.

I am glad I gave pbs a go cause it makes backup and restoring such an easy process and I am still not taking any chances and will be keeping pbs backed up locally cause again realistically it should be enough but it still good to have a cloud backup just in case everything else fails
 
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Reactions: Johannes S
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