How to access to Internal Storage from the SD Card

Volumio Information

Volumio Version:
Hardware: PI4 /Pi3
DAC: HAT HiFiBerry DAC Pro


1/ I’m trying to find the best solution to handle my library either from an external hard drive or a micro SD.

With the external hard drive I had to rescan the library from time to time for unknown reason. Plus, powering the PI + the external hard drive is a bit annoying when you try to limite the number of power supply.

Then I bought a large micro SD card to load my full library. However I couldn’t find a way to load my library expect using the network and shared folder “Internal Storage”.
I tried to see when this folder / partition was by loading the micro SD card on my computer and couldn’t find it. Do you know how to access to the files/ folder? This will allow me to copy my database much faster than using the network (ethernet).

2/ Last, I don’t know if there is some suggestion, but in 4 years of using Volumio I through to the bin about 4 micro SD card. Is there an file format suggested for Volumio / some tips? (I switch off my system everyday and reboot it when needed once a day).
Also I’ve ordered a Linear Power supply 4A which could improve stability in the long term as well not yet received.