I suspect that there is something in the compression pipeline.thanks for the additional numbers! that does indeed look like there is some severe bottle neck happening that we should get to the bottom of..
Because like i mentioned in the Bug Report, even if the way the Backup works with PBS compared to Local-Storage Backup, the limitations are all exactly the same.
Or the speeds are identical between Local and PBS as soon as Compression is enabled (no matter which compression or how many zstd multitasking threads).
With disabling Compression, it feels like every Limitation is removed, the Backup-Speeds go up to 5GB/s here.
With enabled Compression (no matter which/multitasking etc), no matter if Local or PBS, i can't pass 1GB/s.
And in my opinion it has nothing todo with Clockspeeds either because i Monitored the CPU-Utilization during Backuping (Local and PBS), and i don't see any Cores reaching 100%.
But im not entirely sure, since on other side, the Clockspeeds are definitively important, i get on Servers that can reach higher Clockspeeds faster Backup Speeds.
I took me 3 days of trying to find out what the Bottleneck is, as i created my Bugreport...
And i tryed to make PBS-VM Instances and even reinstalled one of both Genoa-Servers with PBS, to have the fastest possible PVE+PBS on the planet, tryed with Local Storage and all tuning options possible on Compression, etc...
Monitored CPU and IO etc...
And couldn't find out what the Bottleneck is and gaved up.
On the returning side of things, it seems like im still Archieving the fastest PBS Backup-Speeds with 1GB/s even with SAS (HDD) Drives on PBS, while others are using NVME Drives and have troubles to reach 500mb/s.
Cheers