I want to store user data (e.g. part of users home directories) on a small file server. The data is well structured and I know which data needs high availability and which data could be archived.

To preserve space I would like to store all data compressed on the file server and lateron export it on DVD. I thought of the following tiers:

1: Recent data that is stored on fast disk space
2: Older data that is stored compressed on disk
3: Even older data that is stored on DVD and last image is still mounted
4: Oldest data that is on DVD but archived in cabinet.

With quota I limit the available space to the size of a DVD so that I can backup it easily.

Now it would be great if you could mount a tar.gz file or could use a loopback device to compress the filesystem where the users could archive their data. Or simply update an archive file. But the contens should be browseable and the directory structure above should remain.

What are your suggestions how to implement this?