[SOLVED] What kind of transfer speeds should I expect?

jessek12

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Jul 21, 2014
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10,510
I have a Macbook talking to a linux VM on my desktop. Transfering files with rsync from the Mac to the VM I get less than 400kB/s transfer speed. An iperf3 test saying I have a bandwidth of 16.7 Mb/s between the two devices. I was hoping for transfer speeds of closer to 800 Mb/s. Is that an unrealistic expectation?

Hardware:
Router: Netgear R6700v3
Desktop: Hardwired gigabit connection (Realtek RTL8111E)
Macbook: 2018 Macbook Pro on 5GHz Wifi. Should be a gigabit connection.
 
Solution
Your problem is the wifi. Those numbers you see represent encoding rates not actual data transfer rates. You get nowhere near those rates.

Iperf is a pretty good test of maximum speed in a lan. What you get in real file transfers depends on many things like the file size. Transferring a large number tiny files take much more time that 1 large one. Still your number is extremely low.

Do you have any ability to test this with ethernet so you can eliminate the wifi as the source of all the problems. You could also be getting error on the ethernet cable but that is not as likely.
Your problem is the wifi. Those numbers you see represent encoding rates not actual data transfer rates. You get nowhere near those rates.

Iperf is a pretty good test of maximum speed in a lan. What you get in real file transfers depends on many things like the file size. Transferring a large number tiny files take much more time that 1 large one. Still your number is extremely low.

Do you have any ability to test this with ethernet so you can eliminate the wifi as the source of all the problems. You could also be getting error on the ethernet cable but that is not as likely.
 
Solution

jessek12

Honorable
Jul 21, 2014
6
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10,510
Yea, testing a 260MB file I get a 17.7 MB/s with scp and 20.93 MB/s with rsync. iperf3 is getting 518 Mb/s.
Are those speeds what you'd expect?

The previous Wifi tests were sending large gopro videos as well.

There's shouldn't be too much of a performance impact if I'm going through a VM right? The host is giving the VM direct access to the networking hardware?
 
IPERF on ethernet should give over 900mbits/sec. Wifi is hard to say even if you have a fancy nic that has 4 antenna and a router that also support it you not get much over 300mbps unless you sit on top of the router.

Virtual machines depending on if you are dedicating the nic or sharing it can slow even ethernet. You are now having your cpu simulate a interface rather than the hardware do the work. If it is dedicated to the virtual machine it function mostly the same as a real nic on a real machine.