And you don't wanna use RAID or LVM...
How about an intricate system of symlinks? You could have directories under the main directory pointing towards the other partition but it will just appear as another directory sub-directoried out...
Here's what I mean:
Let's say you have /home/music
And in /home/music you have:
And you wanna make another directory called:
But you want this directory to have more room because the drive is getting filled up, so you could:
mount the new partition, the larger one, at wherver, we'll use /mnt/data and then symlink to it or even mount it up at that point. For simplicity, let's go with symlink:
ln -sf /mnt/data /home/music/aiff
This will create a directory:
That is essentially pointing at:
And all the music will be placed there, however your software and users will be able to access it by going to:
Welcome to LQ
Would that be something that might help you achieve your goal?