Now that I have my 21.5 - 3.2 - 16Gb - 1TB Fusion, I want to set it up to work optimally. Specifically, I have my entire photo library and ripped CDs on the internal drive. I have yet to work extensively with Lightroom, (I will at times be processing photo shoots of 100 to 200 20MB photos) so I have not yet asked my iMac to use the Hard Drive portion of the drive much at all. It seems to be using the SSD for most of what I do, (documents on Pages, Safari, & my business related Filemaker program which uses an offsite server) and I hardly ever hear the drive, and everything is very quick. I also have an external Toshiba 2T - USB 3.0 - 5400 Drive, which is partitioned for 850GB for Time Machine and 1.15 for files. I have yet to put any files on the external file portion. My computer is additionally backed up daily by Carbonite Is there any benefit for me to transfer the photo files to the external drive and to use that drive when in Lightroom? I gather it would take work off of the internal drive, but that is not too often, and it ought to be dependable for some time, I assume. On the other hand, if I do transfer to the external, I would need to tell Carbonite to back that up, at a nominal additional cost of $40 per year. Also, would the external drive slow up work in Lightroom? As always, thanks in advance for the good advice I know will be forthcoming.