I would like to completely update my old installation on Raspberry Pi 2, still with Jessie OS.
In the documentation of the pre-built image it is indicated that it is compatible with Pi3 and 4, so I cannot use it with Pi 2?
If I wanted to write the feeds on USB stick to further preserve the SD, what is the best way: to use the symbolic links or modify the paths in the settings file? In this case can I avoid creating the ext2 partition?
sorry if I asked trivial questions, I’m not an expert 
It should. Needs a small ‘fiddle’ but emoncms runs fine on my PiZero.
SD life is pretty good with the image so that isn’t an issue. Just remember to backup regularly!
thanks for your answer
the use of the USB-stick is because I already have it and I also use it currently (with simlinks), the backup of the feeds is done regularly and automatically on the nas of my local network
It does.
The “fiddle” Brian refers to is one line in one file. After you’ve flashed the image to your SD card, and because it’s designed for a 16 GB but I could get 32 GB cheaper, with it still in the laptop, I expanded the partition with GParted. Then you need to find the file
/boot/config.txt
find the line(s)
arm_freq=1200
arm_freq_min=600
(the second line might not be there - can’t remember) and replace with
arm_freq=900
arm_freq_min=600
and of course save the file, put the SD card into the Pi and you’re away.
I’m not an emonCMS/Pi expert, so if you want to keep your data and dashboards, Brian is probably best placed to help you.