PBS testimonial (hardware requirements are a joke)

Nov 26, 2021
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Clickbait headline, but I think it is true :)
Maybe others can chime in with their setups and why they need beefy hardware.
Here is my PBS testimonial.

Reading the documentation I was a little bit scared. Especially the storage part seemed brutal.
Turns out it is not that bad and I misunderstood how PBS works.
I wanted to backup 3 destination, each roughly hosting 5-10 VMs.
Mixture of Windows and Linux VMs.

Since some of the PVE are from my clients, I wanted to do it right.
AMD Ryzen 5 8500G, two 120GB SSDs for boot and two 2TB nvme for datastore.
Changed to recordsize to 4M for the datastore (which I think should be a changed default for PBS).
I was for a long time on the edge, if I should just get two HDD and combine them with L2ARC, but then decided that if I need more than 2TB in the future, I could still do that and use the NVME as svdev or L2ARC.

Turns out, the storage performance is not that important. I thought that PVE would create a chunk checksum, send that to PBS and then PBS would check some kind of metadata table or DB on the disk, to see if the checksum is already there. I think what happens instead is that the PVE will get a hashtable at the beginning. So it will check against a local hashtable and only send the chunks that are not on that table. Thank god, otherwise high latency VDSL backups would probably become a problem.

So in reality, not my storage is the bottleneck, but the 1GBit/s WAN of PBS and the 40Mbit/s upload of one PVE location.
No matter if garbage collection or prune jobs, they are under 10 seconds.

Maybe the random 4mb chunk reads when doing a restore profit a little bit from having SSDs, but probably even that would have been fine with HDDs.

If you are going to use an ACME, do it first! I did it afterwards only to realize that ACME changes the fingerprint when the cert gets renewed.
It is also easier to just get a real cert, then you don't have to use fingerprints on PVE and can just leave it empty.

Some things about permission I love, others I don't really like.

Love:
You can give PVE only the DatastoreBackup permission and have a ransomware protected backup system by doing so.

Don't like:
I struggled with api tokens and users.
I want to create an api token for PVE1 that has permission to access /datastore/PVE1namespace.
So I naturally assumed just creating a token with permission to /datastore/PVE1namespace is enough.
Instead I have to create a token tied up to a user.
Why is it combined with a user?
So I have to create the user PVE1user and then create the token with permission for /datastore/PVE1namespace.
And that is not enough either, I have to give PVE1user access to /datastore/ so PVE can read it. Which seems rather stupid, since I explicitly told PVE to use PVE1namespace.

Deduplication is pretty poor. Not because of PBS of course.
Looks like Windows just shuffles and changes too many data even during normal usage.
I currently have 18x backups of each VM and my deduplication factor is only 11x.

All in all, I am very happy with PBS! :)

Unlike PVE, for PBS pricing is a little bit too steep for me. But thankfully that isn't a problem since you let me use the community edition.
Keep up the good work!
 
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Deduplication is pretty poor.
Obviously that depends on the modified data per interval and the "prune"-settings. And it needs a number of backups present to work at all :-)

Both my dayjobs cluster and my homelab show around 30 - with basically "everything daily". If I would run hourly backups the Dedup-Factor would probably rise.
 
Hi,

For deduplication YMMV, for example, if I look at our PBS, it's pretty good with more than 90% of Linux VMs (more than 60% of these Linux machines are Debian), and retention from 14 to 365 days.

2025-12-10T07:57:06+01:00: Original data usage: 10.225 PiB
2025-12-10T07:57:06+01:00: On-Disk usage: 14.638 TiB (0.14%)
2025-12-10T07:57:06+01:00: On-Disk chunks: 15675165
2025-12-10T07:57:06+01:00: Deduplication factor: 715.29

We have critical VMs which backups run every 2 hours, and the other run at least one per day (VM => 93 Groups, 78200 Snapshots).

Best regards,