Alternative USB driver/overlay for Raspberry Pis

[TerryJC]

Probably not a key one like SumpPi

I would suggest Stage or Lady Hanham Butts.

[hamishmb]

Alright, I'll do both, because then I can do the following speed tests:

Old driver - Old driver (for a few pairs of pis)
Old driver - New driver (ditto)
New driver - New driver (for the two pis I've changed).

I shall do this now - best to get as much of this stuff done as possible before uni.

[hamishmb]

I've done all of these speed tests with a 50 MB files transferred from pi to pi over SCP. I know SCP is a bit slow bit it's likely the way we'd transfer data in the real world anyway, as opposed to FTP.

Speed tests before:

Stage pi to sump pi (and vice versa)

Best of three: 3.8MB/s
Best of three (other direction): 2.7 MB/s

Stage pi to Hanham pi (and vice versa)

Best of three: 3.5 MB/s
Best of three (other direction): 3.6 MB/s

Hanham pi to sump pi (and vice versa)

Best of three: 3.6 MB/s
Best of three (other direction): 3.4 MB/s

[hamishmb]

Speed tests after:

Stage pi to sump pi (and vice versa) (sump pi unchanged)

Best of three: 3.8MB/s (same as before)
Best of three (other direction): 3.7 MB/s (up from 2.7 MB/s)

Stage pi to Hanham pi (and vice versa) (both using new driver)

Best of three: 3.3 MB/s (down from 3.5 MB/s)
Best of three (other direction): 3.4 MB/s (down from 3.6 MB/s)

Hanham pi to sump pi (and vice versa) (sump pi unchanged)

Best of three: 3.4 MB/s (down from 3.6 MB/s)
Best of three (other direction): 3.3 MB/s (down from 3.4 MB/s)

Please note, for the first run of sump pi - stage pi tests I think I got the IP address wrong, hence the markedly different speed.

So it looks slightly slower but not significantly, possibly even within the margin of error? I'm happy with how this performs, so shall we see how stable it is over the next week before doing anything else?

[TerryJC]

So it looks slightly slower but not significantly, possibly even within the margin of error? I'm happy with how this performs, so shall we see how stable it is over the next week before doing anything else?

The one thing we don't need on this network is speed! However, we do need reliability, so I'm also happy with the results to date.

Yes. Lets keep monitoring it.

[PatrickW]

I think this was probably a measurement of the encryption speed of the Pis rather than the network throughput.

[hamishmb]

Yeah, probably. However, the new driver is more CPU intensive too, so I thought it might still be useful. Practically speaking, we're only transferring data through SFTP on mode of these machines anyway.

[hamishmb]

Assuming no problems when I check tomorrow, are we happy for me to move the rest of the river system pis over to the new driver?

[TerryJC]

Yes.

[hamishmb]

Okay, all seemed fine so the rest of the river system pis are now using the new driver. I haven't touched anything else.

I figure we may eventually want to do those, but they're probably more tricky to do, especially when the town is open.