Problem with rescan on old Mac Mini

I am new here and in the period of trial.
On my very old (2010) Mac Mini with 8 gig Ram runs now Roon Server.
Now my problem: the music files are on 6 different Harddisks who are connected via usb hubs to 2 usb inputs on the Mac Mini. Not very elegant, I know. Only one of the harddisk gets from time to time new files on board, the other are full. Roon Server was a long time busy with indexing all the files on the harddisks and several times crashed. Every time Roon Server begins anew, she does a rescan of all the harddisks, although she completed importing before she crashed. That takes so much time, annoying!
Is there a possibility to exclude rescanning a harddisk once the scan is completed a previous time? I would appreciate that very much.
For the rest let me say Roon is a marvelous instrument to enjoy music and enrich our knowledge,
Michel G.

Hi @Michel_Goldsteen,

Is Roon installed on an SSD?

How many tracks total do you have in your library?

Roon is installed on an ‘normal’ Harddisk, not on a ssd
The tracks that Roon has imported from all the external Harddisks together are 245425 tracks.