3

I'm using an Raspberry Pi2 Model B as a NFS file server in my LAN.

If I copy a 3.3 GB image file with "rsync -av" from an encrypted drive on my laptop to an encrypted USB drive on my Pi2 I get a transfer speed of ~ 12MB/s.

Does anyone know how much speed I would gain in the same scenario with a Pi3 (just about..)?

You haven't said what kind of speeds you would expect on your LAN for similar kinds of transfers between other computers, and the network itself is a significant factor.

  • Laptop (i7 / 16GB Ram)
  • wifi (300 mbit / 3 meter distance from Laptop to router / just 2 devices in that wifi )
  • Forgot to mention: I have a 1Gbit Lan Adapter on the Pi2

From another computer with better I/O and stronger CPU I would expect a lot more.. at least as much as the wifi can handle.

Only if the Pi currently does this with a very high processor usage, say 75%+. This would indicate it is working hard to deal with the encryption, and might benefit from more horse power there.

Pi2 CPU load is > 75% when copying..

  • Performance on a wifi network is affected more by the number of potentially active nodes, not the distances involved (unless those are excessive/near inviable). – goldilocks Apr 6 '16 at 16:26
  • Thanks for the info! There is an idling smartphone in the same wifi.. nothing else. – Rotareti Apr 6 '16 at 16:47
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Does anyone know how much speed I would gain in the same scenario with a Pi3 (just about..)?

Only if the Pi currently does this with a very high processor usage, say 75%+. This would indicate it is working hard to deal with the encryption, and might benefit from more horse power there.

Otherwise, the bottleneck is the I/O, and as far as I am aware the Pi 3 is the same as all the other models in that regard.

There also a chance this might be improved if you are using the new onboard wifi and that is separate from the LAN9512 USB controller, particularly since you are going back out again to an external drive.

You haven't said what kind of speeds you would expect on your LAN for similar kinds of transfers between other computers, and the network itself is a significant factor.

0

I got myself a Pi 3 and made a comparison.

Both Pis use the same flash storage and the same software configuration. Both Pis are slightly overclocked: Pi2@1000MHz vs Pi3@1350MHz. Both Pis use the same 1Gbit ethernet adapter. Both copy from the same encrypted source to the same encrypted destination.

In said copy scenario

  • the Pi 2 reaches a transfer speed of ~12MB/s with a cpu-core load of 90-100%.
  • the Pi 3 reaches a transfer speed of ~15.5MB/s with a cpu-core load <50%.

The Pi 3 gives me an increase in performance of ~30% over the Pi 2 for this specific copy task.

In this scenario, the Pi 2 has its bottleneck mostly on the CPU. (one core stays close to 100% during the whole copy process) and the Pi 3 has its bottleneck on I/O (USB Controller) its cores don't exceed 50% load.

I hope the Pi 4 comes with faster I/O. The CPU of the Pi 3 already allows for much more even with encrypted drives.

  • The gigabit ethernet device on the RPi doesn't benefit you in anyway. You'd probably be better off getting rid of it and using the RPi 3's built in wifi. – Jacobm001 Jun 2 '16 at 15:13
  • On the Pi 2 it gave me quite an improvement. I haven't tried the build in wifi yet. Thanks for the tip, I'll give it a shot! – Rotareti Jun 2 '16 at 15:22
  • Turns out wifi performance is really bad. All I got from it is 2.13MB/s. I have no idea why it is so slow.. – Rotareti Jun 2 '16 at 20:14
  • @Jacobm001 Why did you say the gigabit ethernet device doesn't benefit? On a Pi2 I see transfer rates of ~200mbps and on a Pi3 I see ~300mbps. Gigabit ethernet devices definitely improve the transfer speed and especially hold an advantage over wifi. The only scenario where they wouldn't be useful is on the latest Pi3 model B+ where the transfer speed of the built-in ethernet connection is slightly better at ~320mbps. – John Hawthorne Mar 27 '18 at 19:24

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