Pi 5. Does running from an NVMe make much of a difference to OpenCPN

[jimseng]

Hello.
I am trying to find out if an MVMe drive makes much of a difference to the feel of OpenCPN compared with a reasonable SD card on a Pi5. I think the performance on a Pi 5 is very good but sometimes there is a little bit of lag when zooming in and out and I wonder if this is due to SD card read speed from the drive into ram. (Maybe switching between different zoom levels?)Has anybody experienced this? I am trying to work out if I can justify upgrading or whether it will just mean the Pi boots faster but won't really improve what is a pretty good experience anyway. I like the idea of setting up the Pi and then cloning to a couple of SD cards and keeping them as backup, but NVMe is supposed to be more reliable. Any thoughts?

[barnakiel]

Pi does not control NVMe. The memory is fast, but your interface is not. So you will be bound with a disk, and this one will be limited by the bottleneck. That is the PCi slot on Pi. (And, I believe, you also need an adapter perhaps).



On a PC (I have NVMe on this machine), the difference in basically anything is about 100x or thereabout. But here we are talking of a memory on a very very broad rail, and plugged directly into the processor's ass.



So, there are gains, for me : esp where there is plenty of data required "at once" (e.g. intensive graphics (e.g. video 4K in raw, processed in RT).


Where the load is less demanding (e.g. digital charting, etc.) you may still notice a slight difference. But otherwise things like OpenCPN are so undemanding that there is no point in expensive NVMe memory where any inexpensive present day alternative works just as well.


SD cards differ quite a lot in how fast you can read them. But, again, a fast SD card on a slow interface will not work fast. You ARE limited by the platform and its interfaces.


(read into Pi5 Pcie standards to understand this, as I imagine this is how you intended to connect the nvm memory (=drive, in your case)



And btw you are also limited by the processing power (or rather lack of it) of Pi.



In brief : yes, there may be some gains, but are they worth it ?



A decent s/h laptop with native NVMe onboard will be a xxx faster platform. Think of this. And not that much more expensive too.



b.

[jimseng]

The trouble with laptops is there just isn't the io of a pi, which is what makes the pi so great for integration on a boat, what with relays, nmea and Seatalk etc. I find the Pi 5 very good as a plotter and the lag is a mild niggle. I guess I am going to have to buy an SSD to see if it was justified or not. Hindsight is great if it doesn't cost.

[barcoMeCasa]

Originally Posted by jimseng

The trouble with laptops is there just isn't the io of a pi, which is what makes the pi so great for integration on a boat, what with relays, nmea and Seatalk etc. I find the Pi 5 very good as a plotter and the lag is a mild niggle. I guess I am going to have to buy an SSD to see if it was justified or not. Hindsight is great if it doesn't cost.

Plus of an SD card is you can copy the entire hard drive as a backup then just swap if there is a problem or you mess it up somehow. Or a spare Pi they're so cheap. I use a Pi4 with 2Gb memory & it's plenty fast enough with mbtiles/cm93.
Never ever gets turned off.

Yet to play with a Pi5 but don't see much point getting one when all's well already. Even running opencpn, playing back music, signalk recording everything to a database, steering the boat with pypilot - amazingly capable little machines for the power & cost. :cool

Also yet to have a problem with the number of writes to an SD card even with the influxdb database being constantly written to though probably gets a new one about once a year. Started with a Pi 1 onboard many years ago, it's just got better since then

[verkerkbr]

A forgotten option is the use of a fast 3.1 USB stick. I use the Samsung Fit plus 64 GB Flash drive with reading speed up to 300 mb/s..

The image can be copied from the SD card, usb stick and NVME HD.

[petter5]

a NVMe hard drive is dependable and extremely fast. Forget other alternative storage solutions, its posible but all of them are "yesterday"
NVMe is so cheap thesa days so the price really don't matter.


Orange Pi 5 have native NVMe socket so no adapter is requred - and run OpenCpn very well
Orange Pi - Orangepi

[barnakiel]

Not sure what you are saying a laptop cannot drive relays ?


Well, it can. Via serial / serial USB, or BT, or wifi (ESP relays).


As for integration - any laptop onboard is better than a Pi - because a laptop has its own power source backup. And a screen. and a keyboard.


Making easy things hard is not the best engineering / design principle. imho.


Pi sucks big way on environmental proofing - their circuits go South as soon as the boat gets a bit wet and hot. - note there is no varnish of any kind on their boards. It is all soldered on and left at this.


ymmv



At least spray some synthetic wax on the thing before you venture offshore.



b.

[barcoMeCasa]

Originally Posted by barnakiel

Not sure what you are saying a laptop cannot drive relays ?

Well, it can. Via serial / serial USB, or BT, or wifi (ESP relays).

As for integration - any laptop onboard is better than a Pi - because a laptop has its own power source backup. And a screen. and a keyboard.

Making easy things hard is not the best engineering / design principle. imho.

Pi sucks big way on environmental proofing - their circuits go South as soon as the boat gets a bit wet and hot. - note there is no varnish of any kind on their boards. It is all soldered on and left at this.

ymmv

At least spray some synthetic wax on the thing before you venture offshore.

b.

You missed IMHO

And imho that's all wrong, fit a Pi, they run for ever & software is rock solid. And you get the chart table back & can do a proper wiring job. IME anyway, been running Pi's 24/7 for years & manty ocean passages, never ever gets turned off. And just works, if it didn't & wasn't reliable it would be off the boat in a moment.

[jimseng]

All interesting stuff.
verkerkbr, I had forgotten about the USB 3 disk option and since I had one I thought I would try it. I Copied my SD card to it and ran some dd speed tests (booting from each, SD and USB).

Sd card write: 34.1 MB/s
Sd card read: 86.9 MB/s

USB3 disk write: 162 MB/s
USB3 card read: 260 MB/s

The read speed is significantly faster with the USB, basically 3 times as fast. However it made absolutely no difference to the Opencpn lag which makes me think that I don't need to upgrade to an NVMe as it probably won't make any difference to this particular investigation.

petter5, I take your point though, NVMe is incredibly cheap now so next upgrade I will consider it, although my hats are stacking up and I might run out of depth in the instrument pod, which I am rebuilding over the winter.

barcoMeCasa, I agree. I have had my Pi4 on the boat for 8 years. I upgraded to the Pi 5 this year as I set one up on a friend's boat and saw how great a plotter they are for so little money. I bought a 10" touch screen for £85.00 and I am really happy with it. I wish I had the space for a bigger screen though. I need my reading glasses for it. But then I need my reading glasses for boiling an egg nowadays. The lag I am talking about really isn't a problem, I just thought I would see if I could improve it and I have concluded that it isn't disk speed so that is good enough for me. It doesn't show up with CM93, only with the UK O charts, which is probably due to the fact there is far more detail and so more to load when switching between chart scales.

barnakiel, It's not just the relays, it's the NMEA in and out, Seatalk in and out, Alternator rpm and temperature, 433Mhz remote. It all fits onto the footprint of a credit card inside my instrument pod and I have somewhere for the coffee to spill when I go about.

[Corsair63]

I have on board Rpi5 (8Gb)(bookworm aarch64) with NVme SSD and I guess for us on board this is the option instead of SD card, doing two or three small tricks in the system that are well explained in the web is reliable and very fast.
for the lag I have too, mainly when doing a fast zoom or loading the GRIB file, but just waiting for a second it isn't a matter of life & death.
I really miss to have a power input of 12 volts, instead of 5 volts, but I'm dealing witn a converter 12/5.

[barcoMeCasa]

Originally Posted by jimseng

barcoMeCasa, I agree. I have had my Pi4 on the boat for 8 years. I upgraded to the Pi 5 this year as I set one up on a friend's boat and saw how great a plotter they are for so little money. I bought a 10" touch screen for £85.00 and I am really happy with it. I wish I had the space for a bigger screen though. I need my reading glasses for it. But then I need my reading glasses for boiling an egg nowadays. The lag I am talking about really isn't a problem, I just thought I would see if I could improve it and I have concluded that it isn't disk speed so that is good enough for me. It doesn't show up with CM93, only with the UK O charts, which is probably due to the fact there is far more detail and so more to load when switching between chart scales.

I've never noticed any lag on my Pi4 2Gb, but then rarely push opencpn that hard, passage planning is usually done on the laptop then copied over to tablet & Pi. An this isn't very fair as the boat is on the hard with not many charts loaded, gps isn't even on but looks about normal. No Ocharts available to test. Plenty fast for me though, it's the boat sound system at the same time which it does very well with a amp hat plugged on top of the Pi
ANd hats of to the youtube kiddies, ain't easy with a phone in one hand 🤣


https://imgur.com/wUhkHo0

[barcoMeCasa]

Originally Posted by barcoMeCasa

An this isn't very fair as the boat is on the hard with not many charts loaded, gps isn't even on but looks about normal.

Just copied over a 3Gb cmap seafloor mbtile of the Atlantic, bit sluggish when zoomed out but zoom into size of about the Med & seems OK. It's actually noticeably faster on the Pi4 than win10 laptop.