Comparison

Backing up Proxmox to S3 — and when not to

PBS 4 can put datastores on S3-compatible object storage, and for some jobs that's genuinely useful. For your working offsite copy — the one you restore from under pressure — the economics and mechanics usually favor a real PBS. Here's the honest breakdown.

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TL;DR

Object storage is a tier, not a strategy.

  • 01S3: good for cold archive copies
  • 02Egress fees bite exactly when you restore
  • 03Hosted PBS: flat per-TB, no egress meter

Contents

How PBS uses S3

Since PBS 4, you can register an S3-compatible endpoint and back a datastore with an object bucket. PBS still speaks its own chunk format — deduplicated, compressed, optionally client-side encrypted — and uses a local cache in front of the bucket. To Proxmox VE, nothing changes: it talks to PBS, and PBS talks to the bucket. The question isn't whether it works; it's what it costs and how it behaves when you leaning on it.

Where chunks meet object storage

A PBS datastore is millions of small chunk files, and PBS's maintenance jobs touch a lot of them:

  • Verification re-reads chunks to re-checksum them. Against S3 that's GET requests and egress-priced bytes for every verify cycle.
  • Garbage collection walks chunk metadata; against a bucket that means high request counts, and request pricing is where object storage surprises people.
  • Restores fetch every chunk the guest needs, at object-storage latency and — on most clouds — full egress rates, on the day you're least in a mood for a surprise invoice.
  • On a purpose-built PBS, those same operations run against local ZFS with NVMe metadata drives — datastore-scale metadata work is what that hardware exists for.

The cost math, honestly

Take 10TB of stored (post-dedup) backup data. Hyperscaler object storage at roughly $21–23/TB/month lands near $210–230/month before request charges — and a full 10TB restore adds egress on top, commonly high hundreds of dollars at list prices. Budget object stores get the storage line closer to $50–60/month, cheaper but still with the operational caveats above, plus running and maintaining the PBS instance in front of the bucket yourself.

A hosted PBS here is $69.50/month at 10TB ($6.95/TB — Dynamic or a Dedicated Instance), with inbound transfer unmetered, outbound included up to your purchased capacity, and no per-request meter at all. The restore that costs three digits in egress on a hyperscaler costs nothing extra here. Prices move; check current cloud list prices against ours — the shape of the comparison holds.

When S3 is the right call

  • A cold archive tier — compliance copies you'll probably never restore, where storage price per TB beats everything and restore cost is acceptable as an exceptional event.
  • An extra, rarely-touched leg of a 3-2-1 layout beyond your working offsite copy.
  • Contractual requirements that name a specific object-storage provider or region.

When a hosted PBS is

  • Your working offsite copy — the one verification runs against weekly and restores come from in an incident. Predictable flat per-TB beats a metered bill you discover during a disaster.
  • When you don't want to operate the middle layer. An S3 datastore still needs a PBS you run, patch, and monitor. On our plans the PBS is the product — connected in minutes on Dynamic, or yours to drive with full WebUI on Dedicated.
  • When restore speed matters. Local chunks on SAS + NVMe metadata, streamed over a 1–10 Gbps link, with live-restore working exactly as PBS intends.

Flat per-TB. No egress meter. Real PBS.

From $6.95/month with the first 1TB included — restore as much as you need without doing invoice math first.

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