Corrupted disc on my old Mac mini
can I back up my photos on a scan disc now before I lose them all?
Question marked as
What do you mean by "scan" disk.
To store a photos library, you need an external USB drive (Directly connected, not ethernet or wifi). It needs to be formatted MacOS extended or APFS. Obviously this will only work if your drive is not so badly damaged it can't read the library.
Then copy the whole library from the pictures folder onto the external drive.
See:
Move your Photos library to save space on your Mac – Apple Support (UK)