Storage Solution

Please allow a slightly different spin from greybalanced's post above. Everything he posted is correct, but there are some ways to trim things a bit. Spent a lot of time playing with various versions of this theme when installing an SSD. While my experiments are with Aperture, the basics should apply to Lightroom.

-- You want the application and your catalog (called the Library in Aperture) on the fastest, emptiest drive you have. This part of the system is read and written constantly, so you want lots of empty space for work files, changed previews and thumbnails, and, of course, your edits. In a MacPro a two disk set up, OS/applications and data is ideal. On an iMac or laptop, FW800 might be a bit less desireable.

-- Your master image files, on the other hand, are written only once and never, ever altered. Let this soak in for a moment. Unlike Photoshop, which is a destructive workflow, in Ligthtroom your edits are all in the catalog and never in your master image files. What's more, you may not even read those files that often unless you are editing at full resolution or printing. (Bit less sure of this.)

So you can comfortably place your master image files on even a USB 2.0 drive and it is unlikely that you will see any performance hit. I even tested masters on a USB drive plugged into a Time Capsule and the results were virtually identical to direct connection.

Some caveats:

-- Obviously, faster is always better.

-- Speed will be more important with larger files, thus a 15 MB RAW will load faster than a 120 MB TIFF. (I do a lot of work with scanned slides.)

-- A dedicated drive for your masters is very nice as it will not fragment. Masters are write once/read many.

-- On a MacPro, a three drive set up: OS/App, Data (catalog), and Masters is very, very fast, partly, perhaps because the I/O is spread. Thunderbolt will open up new options.

Hope this is helpful.
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DiploStrat