I had an Ubuntu system that was working well since 4 years but after some recent update I slowly lost part of the system where the video lower its resolution, booting to new version was not working and sound was lost. I tried to solve the problem but after some days the system was not booting anymore. I bought a new SSD drive and install a new version of Fedora on it. The old hard disk is still on the system.

What is the best way to make that drive available as a data drive mounted in Documents? I want to keep the home directory and settings of software I installed to copy those settings to the new system and delete things I won't use like /var and reorganize things slowly. Right now I only succeed to mount it as read only

-It is 4 TB with 3 partition where only the LVM2 partition interest me to mount. It was a one disk lvm
-SMART indicate the disk is fine
-FSCK indicate there is not problem on it
-A lot of the files are owned by root so I will need to replace all the permission to delete those files

It is not a good idea to mount it directly to your /home/Documents folder. This would be preferable:

Add the drive to your /etc/fstab, with a mount point in /media (or /mnt if you prefer; I use /media for drives that I add to the system), then make a symlink to it under Documents.

The mount was different in /media I could write to it.

This may not necessarily be a good idea - it's likely the versions will be different from Ubuntu to Fedora, not to mention the configurations. Might work, or might cause unusual quirks.Maybe a good thing - that way you always have the old data to refer to/copy. Later when all is done, simply run mkfs on the filesystem and use it for whatever you want.

I don't know how familiar you are with the mount command but, if you currently have directories/files in your /home/user/Documents directory and mount another drive partition there the original directories/files which were in Documents will be unavailable to you until you unmount the new drive/partition.

No, it is the owner and permissions that allow that on Linux filesystems not the location of the mount point.

To find out if it is a file ownership or permissions issue a simple "ls -l" command in the root directory where that disk is mounted (and another as "ls -l ../" in the same location. The output should show that.

Note that if you did mount it to the documents folder, anything within the original documents folder on your main disk would no longer be accessible till you unmounted it again. Quite a good way to hide sensitive stuff to prevent your wife/girlfriend/husband/boyfriend/brother/sister/partner, etc, from rummaging through your computer files when you forgot to log out though!

Play Bonny!

I'd create a new mount point /Data, then put it into /etc/fstab, then link it into your /home directory, change permissions & ownership, (if necessary).