I have a 27" iMac with the 1TB fusion drive and I'm planning on using a USB 3.0 drive as an external scratch drive for CS6. In my research I came across a few things that have raised some questions and I'm hoping for some clarification: 1) I understand that the general idea would be to import the video files to the scratch drive, do everything there, and then once I'm done, put the entire project on the fusion drive for archive purposes (with TM backups and off-site backups, as well). But in this situation, how is one to backup the scratch drive considering that my original imports will be on this drive for now? Is TM an ok way to go. 2) I also read that many people aren't really storing any media on the main OS drive (my 1TB fusion) and that these items (photos, videos) are all going on an external enclosure as well. Is this the case? And if so, is this when people are bringing in the RAID-0 or the RAID-6 type setups? So you'd have 1 external RAID setup to keep the media, and 1 external setup as scratch to work on it all? 3) Do I store the lightroom 4 catalog on the RAID external drive, or on the scratch drive? Thanks very much!