Why don't you sync with the chain on your PC? The processing power of Pi restricts the speed of sync and this might be also a workaround for your problem.
I want to test all the process in a weak environment to tune it
Some thoughts:
The question becomes then how weak an environment do you want?
You are using an external drive, but you can get 512GB good fast name brand SD cards for ~$125 USD (Samsung / Sandisk / PNY) you can get off brand ones that are still OK for less. But their performance sucks.
You are using an external drive, which is good. BUT are you using a 5400 RPM or a 7200 RPM or a SSD?
Setting up the swap space and configuring node are going to be ALMOST the same process, BUT not 100% the same. You are going to get different answers in what is going to get you the best way to do it depending on what else you have. With a good fast SD & SSD you can use more swap with a smaller performance hit to other I/O operations then with a generic slow SD and 5400 RPM drive.
And don't get me started on USB -> SATA adapter quality & speed.
-Dave
For me the task is to use a single PI for multiple tasks. I have a RPi3 with Kodi, and bought an external 7200rpm 8TB disk and connected to it to store my media, and also to serve as a NAS for my home. And I was wondering if it could serve for bitcoin and lightning node, just after I got my new internet connection.
It happens that it can!
I only created the swap file, and started bitcoind with optimized parameters, and it is syncing, very slow, but advancing.
I'm not in hurry for it to finish, but when it finish, I think in couple weeks, I will setup the lightning node there.
