interesting USB conflict on Pi 4 (SSD vs SD card) [NEVER MIND ...] #57720
I've been experimenting with variations of my Pi 4 imaging configurations in Kstars/Ekos.
I recently bought a fast USB SSD to replace the SD card on a Pi 4 (4 GB) running Raspbian. Software installed using rlancaste's AstroPi3 scripts.
The SSD is plugged into a USB3 port on the Pi, and noticeably improves both boot times and application launch times. The whole system feels snappy and responsive.
But I can't really use this system for imaging, at least with my full-frame ASI094MC Pro, apparently because downloading the large image files conflicts with the SSD on the USB bus. Mostly INDI just fails to download the image from the camera completely.
I have been able to get images to download into Ekos by reducing the USB "bandwidth" in INDI settings to 40%, but even with a USB3 cable this takes about 2x as long as using the same camera attached to the same Pi4 using USB2 and a fast SD card.
There are lots of articles on Pi forums touting the benefits of replacing SD cards with fast USB SSDs. Unfortunately I think for astroimaging this is a dead end.
interesting USB conflict on Pi 4 (SSD vs SD card) [NEVER MIND ...] #57727
I and others are using SSDs for imaging, and they work fine. My ASI183 cam creates 40MB raw frames, and those frames are short (30 seconds). I use a 2 sec delay between exposures. I'm not booting from the SSD (yet), but I do run everything from SSD, just using VNC to see what's happening (over wireless). I'm running SM OS (latest release). So, can you say a bit more about your run-time config? Are you running from a laptop using wireless or ethernet & VNC, or ?? Is a laptop the download target or SSD filesystem? In my case, I have the SSD plugged into a powered USB3 hub (in fact, all my devices are plugged into the hub). A final thought about power. SSDs require a good burst of power at startup. Is your power supply to Pi4 up to the job? You might give a powered hub some thought...
interesting USB conflict on Pi 4 (SSD vs SD card) [NEVER MIND ...] #57728
To be clear, I can download images if I turn the USB bandwidth down to the minimum for my camera (ASI094 MC Pro). It just takes twice as long to download as it does with the SD card & the bandwidth turned all the way up. My images are 72 MB each.
Without turning the USB bandwidth all the way down, I can't even download a single image, so adding a delay between exposures won't help me.
This is for a fresh install of Kstars 3.4.3 on Raspbian booted from SSD. I don't have this problem running the exact same image off the SD card. I'm not downloading files to the laptop, just using a laptop to control the Pi4/4GB remotely via NoMachine (faster/smoother than VNC) over my home WiFi network.
I'm not using a USB hub. Thanks for suggesting this. I will try that too. Have had no trouble at all booting from the SSD. No under voltage warnings on the Pi4. Powered using a 5v 3.5A CanaKit AC adapter that came with my Pi4.
Boot time from the SSD is around half what it is booting from the SD card. I had to completely remove the SD card from other Pi to make it boot from the SSD. It's trivially easy to copy the SD card image over to an SSD and then boot from the SSD instead:
For the present, I plan to run with the bandwidth turned to minimum (about 6 seconds to download an image from the camera compared to 3 sec to SD card).
interesting USB conflict on Pi 4 (SSD vs SD card) [NEVER MIND ...] #57739
I'm running from SSD only these days, with downloading each image from my ASI533MC Pro taking in the order of a second. I use the Asroberry server controlled via VNC from my laptop or iPad. I don't touch USB bandwidth etc!
Currently running KStars/Ekos/Indi on a Raspberry Pi 4B 2GByte under Raspbian thanks to Astroberry
Sky-Watcher ED80 Pro with 0.85x FR/Corrector with Canon DSLR on AZ-EQ5 GT mount
Other Sky-Watcher scopes - SkyMax 150 Pro Maksutov Cassegrain and Explorer 150p Newtonian
interesting USB conflict on Pi 4 (SSD vs SD card) [NEVER MIND ...] #57740
If you are using the SD card then the camera data is read from the camera through the USB interface and written to the SD card using the SD interface. Using two interfaces may be more efficient because they may be able to run in parallel using different hardware. The amount of data transferred through the USB interface is 72Mb.
Using the USB SSD the data is read from the camera using the USB interface and then written to the SSD also using the USB interface. That's twice as much data being transferred through what is probably a single connection to the Pi. Is is a surprise that transferring twice the data takes twice the time?
interesting USB conflict on Pi 4 (SSD vs SD card) [NEVER MIND ...] #57747
You could of course just try adding a 2nd "imagine Rpi" RPI4 (1gb maybe) and run the camera on that RPI by itself.
Its just a case of then "chaining" the 2 Indiserver's together if you use Ekos (dont need to do this with CCDCIEL or if you use Firecapture Oacapture stand alone on the "imagine RPI4"). As the comms between the 2 RPI's would be using ethernet(preferably wired) the USB device "hogging" the "Imagine Rpi" will not matter as much.
Indi has the ability to "chain" by default - unless it has been removed since I last used chaining a couple of years ago now.
There is of course a limit to what the RPI4's hardware can do no matter what you do to limit bottle necks! - then its upgrade time to something else more powerful.