I had some SERIOUS space issues on my iMac. The number one rule for a better performing and faster running computer is not to fill the hard drive too much (25% space is a MUST). But I had way less than that left over. My 640 GB iMac was full to the brim, yet backed up to a 2 TB external hard drive (HD) via Time Machine. I wanted to get space freed up on my desktop, but I had a budget of only $ 200. What to do? After getting a bunch of great suggestions, a friend explained the "Master Relocation" on Aperture to me. Keep the previews of all your files on your local machine, but relocated all the "negatives/raws/originals" onto a hard drive. That frees up room, all right, but what to do to back that secondary hard drive up? The Cloud? Another hard drive??
So, after much thinking, and the fact that backing up all my files to "The Cloud" would take 55 days, I decided to do this:
1. Partition the Time Machine HD into two sections: a) Time Machine, and b) Storage. 2. Relocated ( move ) ALL master files to the HD "Storage". 3. Purchase a portable 1 TB HD and copy all master files onto the new HD. 4. Keep the current (2012) master files on the Desktop. 5. Have the desktop backed up completely on the Time Machine HD. 6. Bring the portable HD to work (off site).
This way, if the desktop fails, there is the Time Machine and the Storage HD that keep all files safe. If the Time Machine/Storage HD fails, I have all files on the indexed files on the desktop and the originals on the portable HD. I'm out of luck if two things fail at the same time. But this would be EXTREMELY unlucky and not very likely to happen. In the case of a fire at my home, my indexed files and other computer files would be destroyed, but I can accept that risk, as long as my masters/originals are safe.
Sounds complicated? I made you a little drawing, to explain it better.