What's the best option when the internal hard drive is full?

Hi all,

I am running an iMac 27" with a 2 TB hard drive, which is supported by a 5 GB external RAID for backup (Time Machine and Aperture Vault).

At the moment I have RAW masters located on the iMac in a special folder and linked into Aperture (referenced masters) and the processed JPEG or TIFF files managed within Aperture (library is on the internal drive).

Well, it finally happened and the hard drive is full, and I need to think about how to reorganize my files.

What would be your preferred scenario of organizing files, keeping in mind both speed/performance and safety/backup (i.e., the reason master files are on the iMac and not just on the RAID is because that gives me one more copy).

Ideas I have come up with:

- Get the internal drive upgraded to 3 TB

- Get an additional external hard drive for the master files

- Split the library and move the less used files/projects to an external drive, keep the others on the drive

- Try to move other stuff (e.g., music) to an external drive (not sure that would be enough)

- Keep masters only on the RAID disk

Any opinions, ideally backed up by experience, would be greatly appreciated. If you'd go for an external drive, I'd also like to hear what kind of drive you'd recommend (this iMac does not have Thunderbolt, it is from 2009).

Thanks and cheers,

Bastian