I am running ubuntu server 24.04 on an old HP Proliant DL360p Gen8 with dual 300gig SAS drives in mirrored RAID and 26 gigs of memory.
I have 7days on mine installed in the prestage of setting up a chroot jail. so I have it located at /home/7days/7days.
I have 7days set to run as a systemctl service so it launches as root.
I found that the save file is located here: /root/.local/share/7DaysToDie
I edited serverconfig.xml and uncommented this line: <-- the file is only read once upon startup
<property name="UserDataFolder" value="/home/7days/7days/saves"/>
Now to move the directory structure to the desired location, in my case I used:
sudo CP -R /root/.local/share/7DaysToDie /home/7days/7days/saves
sudo systemctl restart 7days