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Reddit
reddit.com › r/proxmox › what affects dedupe factor on pbs backups??
r/Proxmox on Reddit: What affects dedupe factor on PBS backups??
July 5, 2025 -

Just got this up and running yesterday. Set it for daily backups. It did the first full backup and this morning did the first incremental. Shows only a value of 3.04. TechnoTim had a value like 64. Not sure what he was doing for that but I do think he was doing like hourly backups so that maybe is why. Anyhow just curious what things I could do to possibly increase this value?

On that note, does the garbage collection schedule make any difference? Right now I am doing on PBS pruning for 7 dailys and 2 weeklys (pve job retention is off) and garbage collection every 6hrs. Not sure if this impacts anything but wanted to mention.

I guess what is odd (more with the incremental aspect). I haven't changed a single thing on any of my 10 CTs yet it got an incremental backup and took an hour. Still better than the almost 3hrs it too for a full backup but confused why it was so much if it's just the difference. Since nothing changes shouldn't it be close to nothing?

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Reddit
reddit.com › r/proxmox › pbs deduplication zfs only?
r/Proxmox on Reddit: PBS deduplication zfs only?
June 8, 2022 -

Hi,

so im currently testing the proxmox backup server für my vms. I was wondering if the deduplication / dirtybit only works with zfs or if it also works on "normal" ext4 formated disks (mounted directory).

Best

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Reddit
reddit.com › r/proxmox › zfs deduplication of pve backups?
r/Proxmox on Reddit: ZFS deduplication of PVE backups?
November 11, 2024 -

I'm using Proxmox at home to host the usual things. One ZFS NVMe pool for all the containers/VMs and one ZFS HDD pool for nightly backups.

I just setup a second PC with TrueNAS for some "just in case" backups of the backups (from PVE and other sources around the house).

Each VM has 1-2 dozen nearly identical backups, so I decided to try ZFS' deduplication feature. I copied over backups for 4 VMs (500G total) and was shocked to see no gains/efficiency from the deduplication, not even 1.01!

Some of those backups are from a VM that was powered off, so the original disk was definitely unchanged. Shouldn't the resulting backups be bit-identical? Does anyone know if Proxmox includes some metadata that might spoil block-level deduplication?

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Reddit
reddit.com › r/proxmox › proxmox backup server and dedup
r/Proxmox on Reddit: Proxmox Backup Server and dedup
August 10, 2025 -

I am in the process of migrating from Veeam to PBS, and there are some differences but it all seems managable for my scenario.

One detail I can't seem to find clarified, that maybe someone in here knows: dedup on PBS, is that across a single VM's backups, across whole datastores, or globally?

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Reddit
reddit.com › r/proxmox › correlation of zfs dedup, compression and proxmox backup server
r/Proxmox on Reddit: Correlation of ZFS dedup, compression and Proxmox Backup Server
November 18, 2020 -

Today I played around with some settings in ZFS and Proxmox Backup Server. I use Proxmox Backup Server with a ZFS raidz2 as storage for the Backup space. The ZFS pool was created manually without the proxmox-backup-manager command.

I noticed that the WebUI shows a deduplication factor of (in my case) 94.02 but the zfs pool shows dedupratio 1.00x.

Does Proxmox Backup Server not use ZFS' deduplication functionality? Should I enable deduplication and compression in the ZFS pool? Which compression algorithm should I use?

EDIT: I have tested a bit with ZFS and Proxmox Backup Server for quite a while (both hardware and VMs) and ZFS' deduplication and compression have next to 0 gains. As pointed out by the comments deduplication does not make sense as Proxmox stores backups in binary chunks (mostly of 4MiB) and does the deduplication and most of the compression there. ZFS compression with zstd-12 ended up on a compressratio of 1.02x which is not very significant.

TL;DR It's not necessary to use ZFS compression or deduplication because it's both already handled by Proxmox's way of storing Archives and Block Devices.

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Reddit
reddit.com › r/proxmox › pbs deduplication of incoming backups
r/Proxmox on Reddit: PBS Deduplication of incoming backups
September 8, 2023 -

Hi everyone,

my datastore is at about 40% usage after deduplication. When I run a new backup however, it quickly fills the whole datastore and the following backups fail.

After making some space I’ve run an Garbage collection which worked last time since the backups failed a few days ago. Situation released the following night and now the GC only marks the chunks as „pending removals“. On the Proxmox Forum a staff member mentioned, that new backups are protected 24h from GC, so that they are save while still being written.

How do I set this up, so that my datastore doesn’t blow up every time I run the backup?

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Reddit
reddit.com › r/proxmox › pbs backups from several pve hosts using same vmid
r/Proxmox on Reddit: PBS backups from several PVE hosts using same VMID
March 18, 2024 -

I took over the mgt of 6 different hosts and a PBS. The PVE hosts are not in a cluster so standalone and I have a suspicion that, because of the fact that vmids are reused on multiple hosts, backups are not lining up well and might be overwritten or unavailable for restoring.

So my question is: should I always use unique vmids for my vms to keep backups healthy?

Top answer
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If you have to use the same id of multiple standalone hosts (for whatever reason) you can seperate the backups via namespaces on the PBS. Another option i use (in addition to namespaces) is to prepend my vmids with an identifier id of my host. e.g. i have a host with the name pve09. the vmid prefix for all my vms would be 09 which results in 9101 for example (the leading 0 is lost)
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as a part of the backup job you can create a note per backup that can dynamically take clarifying info https://pve.proxmox.com/pve-docs/chapter-vzdump.html#vzdump_notes Backup Notes You can add notes to backups using the Edit Notes button in the UI or via the storage content API. It is also possible to specify a template for generating notes dynamically for a backup job and for manual backup. The template string can contain variables, surrounded by two curly braces, which will be replaced by the corresponding value when the backup is executed. Currently supported are: {{cluster}} the cluster name, if any {{guestname}} the virtual guest’s assigned name {{node}} the host name of the node the backup is being created {{vmid}} the numerical VMID of the guest When specified via API or CLI, it needs to be a single line, where newline and backslash need to be escaped as literal \n and \\ respectively. in my clusters I use dailyStop - {{cluster}} - {{node}} - {{vmid}} - {{guestname}} twoHourlySnapshot - {{cluster}} - {{node}} - {{vmid}} - {{guestname}} to denote backup type and info where there may be overlapping vmids within the same cluster namespace as I also blow away and rebuild stuff frequently. I may need to look into separate node namespaces. By automating the details in the notes, I have 5 backup jobs for a 4 node cluster instead of a huge list. 1 staggered per node (on 15m centers between 0200 and 0245) daily full stop job, and one every 2hr on the hour snapshot job that covers all nodes. Also I need a long short term memory, e.g. retention policy, but a short longterm memory in backup for those that get blown away recently and need to be restored. I keep the last 1, 12 hourly, 7 daily, 4 weekly, 12 monthly and 1 yearly. use https://pbs.proxmox.com/docs/prune-simulator/ to see your prune schedule on a calendar. There's a search in PBS content which helps as I use a service descriptive name for my nodes in PVE and a fun name in the guest. So in the last 24hr I have 13 backups but total for a year I have 37 backups total per vmid in each namespace. Even with all that my utilization is super tiny: Usage 5.89% (341.91 GB of 5.80 TB) Backup Count CT 15 Groups, 204 Snapshots Host 0 Groups, 0 Snapshots VM 131 Groups, 1674 Snapshots Stats from last Garbage Collection Deduplication Factor 113.90 The one thing I think I'm missing is an off PBS backup in case there's a PBS issue. I think I'll set up a VM in my NAS and do a sync job to a PBS instance w/ datastore there. This setup has saved my bacon more than once. PBS is my favorite PVE accessory. It's a super duper!
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Reddit
reddit.com › r/proxmox › what wizardry is this? i'm just blown away.
r/Proxmox on Reddit: What wizardry is this? I'm just blown away.
March 8, 2024 - This even more compounded when you take the fact that there’s usually only going to be 1 full backup of the data while the rest is incremental. Put deduplication on top of that and you end up with that right there. I’ve got about 20-30 vms/containers backing up through PBS and I’m only retaining 5 backups.
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Reddit
reddit.com › r/proxmox › are the pbs backups incremental? how many to keep?
r/Proxmox on Reddit: Are the PBS backups incremental? How many to keep?
August 2, 2024 -

Hey guys first sorry if this has been asked before I found a few post but nothing really answering in a simple way my doubt.

So I have a PBS machine and I'm doing backups of my LXC and of some specific shared folders in my PVE.
My question is to confirm if the backups are truly incremental and if so do I need to keep a specific number to allow recovery on is he smart to always keep all the necessary data even if I'm deleting all but on backup of a specific LXC.

Also how is it possible that, even counting the space occupied by one single snapshot of each container, the total occupied space 11gb is smaller than adding those up? Is it due to the compression?

Thank you in advance ❤

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Reddit
reddit.com › r/proxmox › proxmox backup server datastore deduplication factor math?
r/Proxmox on Reddit: Proxmox Backup Server datastore deduplication factor math?
September 26, 2022 -

So I've put Proxmox Backup Server into production in my org as we move over to PVE from Hyper-V. It is doing a great job replacing Retrospect and Unitrends. In my Unitrends and Retrospect systems, I can run a report that tells me the rate of deduplication of the data I'm storing so I can see if we're storing a lot of data that is vastly different at the block level, or if we're storing a lot of data that is not changing much at the block level from day to day.

In Proxmox Backup Server, on each of the datastores I have a "deduplication factor" line and then a number. In my case the number is 177.09. The issue is I'm not able to find any documentation on what this number means or how it's calculated. Did I miss something? I can't seem to figure out what is changing it either. It has gone up and down over the past month with no real pattern I can work out.

Any help is appreciated. I've already poured over the documentation for PBS for hours and can't seem to find anything.

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Reddit
reddit.com › r/proxmox › pbs backup size question
r/Proxmox on Reddit: PBS backup size question
January 6, 2026 -

Hi, I am trying to understand how pbs stores backup.

So i know pbs has deduplication and only stores incremental changes. But my question is .

So i have a vm running on proxmox server with 4tb ssd.

Proxmox occupies 100gb ish for the os. I have 2 lxc assigned 8gb disc.

I have another vm running with the remaining disk allocated for it's vda,

Basically / shows 3.2t but only consumes at the moment 45gb of actual data.

Now if I backup with pbs.

Is it going to backup the entire 3.2.tb vda initially or just the 45gb of data?

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Reddit
reddit.com › r/proxmox › why use pbs when pve can do essentially the same backups to a nfs/cif share?
r/Proxmox on Reddit: Why use PBS when PVE can do essentially the same backups to a NFS/CIF share?
September 4, 2021 -

I got my Proxmox server up and running and I created a NFS share on my DS920+, then mounted it in the PVE gui. I setup nightly snapshots of the VM and LXC running on it to the NFS share/mount. After reading around, I realized that PVE is not backing up any of it's config files or settings. I found shell script to make backups of all PVE configs and save them to the DS920+ and that is nice and all, but why would PVE only backup guests and not any of the core config?

I searched around and came across Proxmox Backup Server and found that I can run it in a VM on my DS920+. Perfect! This should solve my full backups needs! Wrong! It appears that it only backs up the guests, just like PVE. Who would have thought PBS would offer essentially the same backup functionality PVE? I mean it is called Proxmox Backup Server??

What does PBS offer that PVE doesn't as far as backups go?

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Reddit
reddit.com › r/proxmox › proxmox backup server setup for home use
r/Proxmox on Reddit: Proxmox Backup Server setup for home use
March 2, 2024 -

Hello,

I run a small PVE server that hosts several home projects like Home Assistant, Nextcloud e tc.

I bought a second mini PC to run as a backup server. I would like to run Proxmox Backup Server on it. However it would be cool if I could also run other backup services on it (e.g. Duplicati target for our PCs).

How would I ideally do that?

I could run PBS as a VM in PVE on the backup machine. However, that requires me to set the disk size of the backup VM and changing it would be a hassle, correct?

Which file system would you use on a backup server with only 8GB of RAM? Still ZFS?

Thank you for your input!

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Reddit
reddit.com › r/proxmox › i wrote a hands-on proxmox backup server guide for homelab and small business. setup, with screenshots, and the ssd fix you helped me find.
r/Proxmox on Reddit: I wrote a hands-on Proxmox Backup Server guide for homelab and small business. Setup, with screenshots, and the SSD fix you helped me find.
May 18, 2026 -

I run PBS on a $150 fanless mini-PC backing up 21 VMs and 2 containers to a Synology NAS. Dedup factor 25x, 1.77TB used.

The guide covers setup, installation, verification, and pruning jobs, retention policy gotchas, PBS vs Veeam, and my full homelab setup with screenshots.

Some of you helped me last week when I posted about my 8.5-hour verify times on NFS. Based on your feedback, I bought a Lexar SL300 USB SSD and set it up as a second datastore. Full verify dropped from 8h 35m to 1h 54m. Daily verification with Skip Verified now takes 2 seconds.

https://edywerder.ch/go/proxmox-backup-server-reddit

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Reddit
reddit.com › r/proxmox › reduce size of backups
r/Proxmox on Reddit: reduce size of backups
September 7, 2022 -

running 8 containers and 2 vms. daily backup is around 12gb in size even with zstd compression. I see a lot of redundancy in the content of the containers (the base system from the distro), but this can't be leveraged because each container is backed up individually

is there a way of optimizing the size of the daily backups? was thinking of a hard separation of os and data using two volumes , and only running backup on the data volume. but this would mean that I would have to setup the system from scratch /ansible in case of recovery rather than just reading in the archive file

any hints? thanks

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Reddit
reddit.com › r/proxmox › newbie here: what are the benefits of proxmox backup server along with pve home server?
r/Proxmox on Reddit: Newbie here: What are the benefits of Proxmox Backup Server along with PVE home server?
March 16, 2022 -

Beginner here. Recently I started running a PVE with 6 VM+Containers in a home server machine. It works fine for last 4 months. Now I have a spare Intel NUC with a 2TB drive storage connected, installed with PBS as trial.

  1. Tried integrating PVE with PBS and able to run VM backup jobs configured in PVE with PBS as detination. This is good. But currently I am able to achieve the same with a network drive as destination. What is the value addition with PBS?

  2. Currently I do backup of PVE host with "zfs send" to network drive. I don't see option to backup PVE host through PBS. Am I missing anything else?

  3. There is a TrueNAS VM runs on PVE. This VM hosts most of my home data. I would like to backup this NAS drive to PBS. Is there any TrueNAS + PBS integration possible?

  4. What are the other features which is good to try and use? I would like to know the value addition in running a PBS.

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Reddit
reddit.com › r/proxmox › veeam vs pbs backup
r/Proxmox on Reddit: Veeam vs pbs backup
April 16, 2025 -

I have used both veeam and proxnox backup. Pbs is very integrated and works well. Veeam is better on space and has better de duplication from what I can tell. What’s generally recommended to backup proxmox?

Side note if you add a second ssd drive to your server don’t use zfs. It crashes the whole server. I had to format the second drive to ext4 for the added space to work for veeam without crashing (virtual drive placed on the ext4).