PBS Sync to one server is very slow

itscrispy

New Member
Oct 18, 2025
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Hi there! We are rolling out PBS across our systems to replace a commercial backup software and are loving it. Our setup is:

  • HP G9 at the datacentre with the Proxmox boxes
  • HP Microserver at remote site 1
  • HP Microserver at remote site 2
Everything works very well from the G9 to remote site 1. No problems, syncs fast, all is good. However, the remote site 2 sync from the datacentre, is incredibly slow.

Both remote sites are connected to the datacentre with 1Gbps links. When synching to remote site 1, we get around 700-800mbit, as is expected once factoring in overhead and other network activity, however, remote site 2 doesn't seem to ever get much above 110mbit. Theoretically, both sites have the same setup, except the PBS version at remote site 2 is slightly newer.

We've done all the basic tests to ensure we haven't left something out. Here are the fio tests on the disks from Site 1 and Site 2.

Site 1:

Screenshot 2025-10-19 094653.png
Screenshot 2025-10-19 094720.png

Site 2:

Screenshot 2025-10-19 094800.png
Screenshot 2025-10-19 094819.png

Site 2 results are slightly slower - but we can attribute that to the sync that's running.

Speedtest results from the Site 2 PBS to the internet and then from the Site 2 router to the Datacentre router show no issues:


ST.png

Screenshot 2025-10-19 095339.png


We have no limits or anything else set anywhere in PBS. Everything is unrestricted and the hardware at Site 1 and Site 2 are the same - the only notable difference is the PBS versions. If it's relevant, the PBS version at the datacentre is 4.0.15.

I can't think of any reason why we're seeing such a significant speed difference and how to fix it. Any suggestions would be much appreciated.