

What I’m noticing more, is that you can keep a consistent 11.4MB/s, this feels relatively close to what you’d usually pull through a 100mbit/s link (after accounting for overhead). If that’s the case, it shouldn’t matter how the NFS client decides to chunk the data, for how much throughput there is to the NAS. Which means you’re looking at a broken NFS server that can’t handle large single transmissions.
If it’s not the case, and you’ve got a faster network link, it seems that the NAS just can’t keep up when given >2gb at once. That could be a hardware resource limitation, where this fix is probably the best you can do without upgrading hardware. If it’s not a resource limitation, then the NFS server is misbehaving when sent large chunks of data.
Basically, if your network itself (like switches, cables) isn’t broken, you’re either dealing with a NAS that is severely underspecced for what it’s supposed to do, or a broken NFS server.
Another possibility for network issues, is that your proxmox thinks it has gigabit (or higher), but some device or cable in between your server and NAS limits speed to 100mbit/s. I think it’d be likely to cause the specific issues you’re seeing, and something like mixed cable speeds would explain why the issue is so uncommon/hard to find. The smaller buffers more frequent acknowledgements would sidestep this.
Do note I am also not an expert in NFS, I’m mostly going off experience with the “fuck around and find out” method.




Hell yeah! 10x speed improvement for free!