excuse my noobiness i only have the rasberry for a day and it was a rather spontaneous buy so i have not gathered much infos yet.
i wonder if i can run apps parallel to octoprint?
i would like to use it as printserver for my epson printer and wifi extender too.
but i have no clue if that is possible with octopi as OS.
as i said i have no experience with rasberry pi, octopi or linux yet.
A printserver should work.
But wifi on a Pi. Nooo 
The Pi has a bad design. All the hardware are connected to a single usb port.
Buying a repeater is less pain.
Blockquote But wifi on a Pi. Nooo
The Pi has a bad design. All the hardware are connected to a single usb port.
ah. ok thanks.
i thought i might try it because there are so many WiFi extender projects to find on the Internet.
so how i understand it after a bit of reading:
octo pi (the IMG file) is basically a normal linux OS but without a GUI.
octoprint is an app that is pre configured to run on octo pi.
but i can also install and run other softare parallel to octoprint.
Yes octoprint is "only" a application which came bundled with the raspberry pi distribution octopi which is based on raspbian.
My setup is currently a baytrail board (j1900) with 4 GB ram 120GB slc SSD 450Mbit wifi card.
1x C270 +1x c310 logitech webcam, a 120w pico psu with 60W power supply.
Running Fedora 30 and 32 octoprint instances.
3 Printers are connected: 2 selfbuild Prusa i3 Printers and a MakiBox.
The other 29 instances are just for developing a software i currently working on.
Ah and 32 mjpeg-streamer instances (30are sending a changing test picture)
Consumes 8-10W relating on load.
It also runs a unify controller within a docker container.
You can't do this on a rasbberry pi 
i will start with adding a GUI to octo pi…
i have not touched commandlines and terminal tools much since DOS days.
i am happy that it was so easy to get octoprint + webcam running.
This is not true. The WIFI on the new RPI3 is not connected via the USB bus. The ethernet is now gigabit even though the max capacity of the usb bus is 480Mbps. This means that ethernet is now getting access to the full capability of the usb bus.
The RPI design is actually genius. At that price point; absolutely genius.
You can install anything parallel to it that you like. Most likely you won't slow down OctoPrint by much anyways.
I dunno if I'd agree with that statement. I routinely monitor the four cores of my Raspi 3B during a print job and I would say that printing a job and streaming video is a good load for those four cores. Just bringing up a new browser during a print job slams one of the cores to 100% for about a minute.
Unless you're a developer, I don't think I would try to maximize those unused clock cycles on your Raspi as an OctoPrint instance. Buy another Raspi, they're cheap.
The 3D printer attached to the Raspberry Pi should be considered a real-time device. By this I mean that the timing of sending commands to the printer is critical to the success of the print.
In most prints, the RPi has "spare cycles" that can be used by other applications. As long as you are aware of the resources required when 3D printing adding those other applications should work.
Except it's not that at all; not by a long shot. Rasbpian isn't a real time OS. Yes slowing down the system will cause delays in the transmission of commands between OctoPrint and the machine.
Exactly. Just trying to make sure that @maltepaas doesn't add so much to his RPi that the print quality suffers.
Blockquote doesn't add so much to his RPi that the print quality suffers.
no, i will use it mainly for octoprint.
and maybe i will use it as printserver for my old epson R2880.
the wifi extender was just an idea.
This is not true. The WIFI on the new RPI3 is not connected via the USB bus.
Ok i checked that but now i wish it would be connected to the USB port.
The wifi is connected even worse than the USB2.0 m)
It is connected Arasan SDIO / because the Raspberry has no pci-e.
It runs at the pi with 41,6 MHz and 41,6*4bit -> 166 Mbit Max.
Maybe you can transmit 90-120Mbit but normally it is max 60% of the max (depends on the band)
So yeah 100 mbit.
Ok it doesn't kick the cpu because the encryption is handled on the chip.
So it is "just a little better"
The rest -> one USB port.
Still garbage.
I have only one raspberry pi3 left for playing bomberman.
It is actually the same on the RPi 0W and the reason why that has so horrible CPU load issues if there's load on the WiFi nic.
Get yourself a Pi3 or 0w, run top and then cause some traffic on the WiFi interface (e.g. by wget'ing a big file from somewhere on your network). You'll see load spikes on the/one CPU of up to 60% caused by the kernel driver.
but running a raspberry 3 with a GUI should have no effect on print quality?
i want to use RealVNC so i would like to have it boot the GUI.
A desktop environment is pretty much the most heavyweight thing you can run apart from bitcoin miners or similar stuff. It can work. Or it can't. I personally do not recommend it and instead strongly recommend to run the server headless as it was meant to be. Any arbitrary desktop component might at any point start gobbling up CPU resources which then negatively affect your print job. I would not want to risk that.
Why do you want to be able to run a VNC server? What is the goal here? OctoPrint offers a web interface precisely so you do not have to run a heavyweight desktop just to monitor your print. And running a browser is even worse than just the barebones desktop environment, especially if it's a browser showing OctoPrint's web interface since the whole web interface was written in a way to offload as much work from the server as possible so that that can concentrate on feeding the printer, and by running it on the same system you'd effectively nuke this whole concept.
ok i have to explain this a bit i guess.
i really hate working with linux to be honest.
i started with a ZX81, i build with my father around 1980.
so i am not a computer noob but i always hated working with linux.
i tried it in the late 90s for a week.... hated it... tried it again 8 years later... hated it.
DOS was bad enough.. i am a visual guy.
i rather cross a checkbox or doubleclick on an installer then having 5-6 commands i have to write on a prompt. strange i know.
just now i want to install a text editor like notepad++.
i have to spring to hoops and compile notepadqq for my raspberry.
sudo apt install -y qt5-qmake......... g5-dev libuchardet-dev libqt5webkit5-dev libqt5svg5-dev qttools5-dev-tools
git clone https://github.com/notepadqq/notepadqq.git
cd notepadqq
git checkout -f v1.4.8
./configure --prefix /usr --qmake /usr/lib/arm-linux-gnueabihf/qt5/bin/qmake
make
sudo make install
just to get a text editor installed .... that is NOT userfriendly.
so why do i want a GUI. not for printing.
because i like to make edits with a graphical interface not the 1983 nano text editor.
i may want to try other programs on the raspbbery when i am not printing.
but i dont need the GUI running all the time.
i thought i could just start it on demand.
but the startx command does not work on the terminal (-bash: startx: command not found
).
i read that is used to start the GUI on linux (well im a linux noob. what i knew about linux i have long forgotten).
so i don´t know how to start the GUI on demand.
I know exactly how you feel. I don't like the command line either because of the productivity loss. We are being pushed toward the cmd line by the the powers at be. Just the other day Microsoft announced that they are releasing a Microsoft Terminal, to replace the 30 year old commandline interface that grew up with windows (so they can support emogies I guess).
To aswage some of your frustrations try navigating the file system with WinSCP. It at least takes care of you having to navigate the directory structure copy files and having to work off of that > interface. Only think it can't do is execute programs and return the result.
EDIT: And since alot of the hardware is exposed like the filesystem /sys/class, it means you might be able to manupulate the physical pins on the RPI (on in my case beagle bone) via WinSCP.
Tut, tut... you're never too old to learn something new. At some level, you expect to compromise with a $35 computer and not to expect that it would have the performance of a $300 PC, right?
You: "Dear Raspberry Pi, since I don't wish to learn some terminal versions of commands I'm going to add weight to your existing load in the form of a GUI and a VLC service."
Raspi: "help...!" /smallvoice
Learn some LInux. And no, I don't mean "so that you can compile a GUI-based version of a Windows Notepad" either. There's really a short list of commands that honestly make up perhaps 80% of what you'd ever need in Raspbian:
sshsudocat, less, grep, find
apt-getreboot, poweroff
nano, touch, chmod
whichIt's like the difference between visiting Europe and only-speaking-English versus knowing-how-to-say-a-few-things-in-French-and-German. Either way, you'll survive. But in one case, you'll likely enjoy yourself more.
Blockquote Tut, tut... you're never too old to learn something new. At some level, you expect to compromise with a $35 computer and not to expect that it would have the performance of a $300 PC, right?
no.
where exactly did i say i expect performance of a 300$ pc can you point me to that?
what i did wrote but you missed is this:
Blockquote so why do i want a GUI. not for printing .
i said i want to run GUI and a texteditor on it IF possible.
i don´t want to run fusion360 or photoshop on it.
why build a realVNC server into octopi when everyone and his grandma tells you not to use it?
what is the reason to have it in octopi in the first place then?
again i don´t want to use realVNC WHILE i am printing.
i don´t want to monitor the raspberry with realVNC while printing.
just to make edits when not printing.
maybe i was not clear enough.
my question was if i can have the "boot into GUI" enabled all the time.
not that i do things on the GUI or even have realVNC running while printing.
just so that when i am not printing and want to fiddle around with the raspberry i COULD use realVNC. without going into the settings and change boot options.
i honestly thought (naive me) that a raspberry 3 running linux is able to handle a GUI and some load (octoprint). i did not think it was such a ridiculous thing to ask. but now i know better.
but i never expected performance of a PC.
I did some initial work with adding the PIXEL/Desktop to OctoPrint, a TFT screen, a Conky interface for monitoring performance and VNC as well.
The VNC is useful for documentation purposes since it allows you to easily do screenshots of what's on the TFT, for example.
You can leave the boot-to-console if you'd like from sudo raspi-config but I have a feeling the Desktop system is still there, just not directed to that console.
I just wouldn't recommend this for a production printer, to be honest and especially not a delta sort of printer (didn't see what kind you had).