Slow network transfer speeds with macos guests file sharing

[trodemaster]

We have received some reports of very slow transfer speeds from macOS guests. 

Host: macOS 12.6

Guest: macOS 12.6

vmxnet3

Tried NAT and Bridged

Host is getting 300 MB/s transfers and the guests are seeing 50 MB/s. 

Is this a known issue? 

[Technogeezer]

Are you running the Tech Preview on an Intel Mac or Apple Silicon Mac? I'm assuming Intel Mac because it's almost impossible to get macOS virtualized using the Tech Preview on an Apple Silicon Mac.

What is the host Mac (cpu and memory configurations), and the virtual machine configuration (virtual cpus and memory)

And please describe how you are performing file sharing? 

[trodemaster]

We have internal reports from a team that has a number of different systems showing the same issue. For my repro test I'm using the following. 

MacPro 2019 16 Core 256GB RAM macOS 12.6 10Gbit ethernet

VM is macOS 12.6 8 Core 32GB RAM 100GB NVME disk

Setup file sharing on the host system with the internal NVME drive as the target. Mounted the share via the finder and then ran AJA speed test against the share.

[ColoradoMarmot]

That's not unexpected - you're running through multiple network stacks, as well as the virtualized adapter.  Shared folders are the better option.

[RDPetruska]

VMware Shared Folders feature does NOT use the virtual network adapter - it uses backdoor methods of communication with the virtual machine.  If you want to test network speed, you need to use standard SAMBA file sharing (or whatever Mac uses natively in this case, since both your host and guests are Mac).

[trodemaster]

Hey friends this is not my first dance here...

I'm not testing the shared folders feature if that was not clear. The macos file sharing uses samba and it pushes a few hundred MB/s between physical hosts with the same hardware. 

My question is around the TP version of fusion being slow at filesharing traffic with the current version of fusion. It's not an issue with a specific host as the reporting team has the same issue with a bunch of systems in our server room. 

I know that Fusion has adopted the macOS network stack for recent versions of the product and I'm wondering if it'a know issue with that stack being slow with large transfers? 

[Technogeezer]

It's possible that what you're seeing is an artifact of the switchover to using Apple's frameworks for Fusion 12 and later on Big Sur and Monterey. What isn't clear is if its due to an Apple issue or an issue introduced by the "refactoring" of the VMware networking stack to conform to Apple's new kext-less frameworks. I've seen some wonky behavior out of the networking stack in Fusion 12 and the Tech Preview (especially where NAT networking is involved). 

A thought. You wouldn't happen to have any AV product running on your host Mac? I found that trying to use SMB sharing on a Mac when I had Norton 360 installed was dreadfully slow. I uninstalled Norton and the file transfers became a lot faster. 

[ColoradoMarmot]

I believe they've done a lot of work on the networking stack for the TP.  @Mikero any thoughts on this one?