To elaborate on the title, I just want my documents (text, media or whatever) to be safe from deletion in case of a re-installation of Ubuntu and at the same time to remain accessible now. Just as things are in Windows: no matter how many times you re-install the OS in c:, the data in other partitions remain intact.
At the time of installing the Ubuntu, I did create extra partitions for the purpose but couldn't mount them. I was warned that the partitions, unless mounted, would be unusable (and that is what has happened), but I wasn't sure where to mount them: /usr, /usr/local? Some answers to similar questions in this forum seem to suggest /data or /workdata as mounting points, but I don't remember any such options offered during installation. I have even gone half-way through a mock re-installation but still haven't found those options.
By way of a bit of extra information, I have used Ubuntu 14.04 for a number of years. It was installed in the c: drive of a Windows system, and all the other partitions remained intact, in the form of 'media/.../ntfs'. They wouldn't mount at booting, but their icons showed up on the launcher. A click would mount them and the Ubuntu system could freely communicate with them. A similar configuration will do for me.
I would be grateful for any useful advice from anyone more experienced than me.
gparted, KDE partition manager or whatever program you like to create partitions, then just select them with the installer but don't format them... – guiverc Jul 05 '21 at 11:13ubiquity,calamaresor whatever installer is being used;ubiquityfor Ubuntu Desktop), and create there. If for example I want to split a 80GB disk half for system & half for user data, I'd not give 40GB to each, but create two partitions 39 & 41GB as it's easier to find them when they're not the same size (sizes only example). I'd not use a foreign (NTFS) layout, butext4or a fully POSIX compliant fs to avoid problems... NTFS is for windows – guiverc Jul 05 '21 at 11:24