Thank you everyone for your thoughts. I was thinking of a 500GB drive to dedicate to LR work, and from Misirlou's post, it's clear that for my needs that's plenty -- I have a mere 5000 or so images, am just beginning to shoot in RAW, and will be more likely to add 150 images in 2+ months rather than in a week. I certainly will back up the drive to a larger external, probably a terabyte.
Misirlou, I'd appreciate any tips about setting up the system so your one drive can be used identically on several computers (I'll only use two rather than your four).
Thanks again!
David
The short answer is to go download Seth Resnick and MR's "Where The &*%$ are My Pictures?" video series, and watch it the whole way through about 5 times. That's what I did.
You'll need to copy the specific Lightroom configuration files for all of the things you need to do, to each computer where you do them. For example, I established several develop presets for each of the cameras I use. I stored those on my external drive once I thought they were mature, and copied them to the appropriate location for each of the working computers. These file locations differ rather dramatically by operating system manufacturer and version, but they're easy to find with search tools. For example, search for a folder called "Develop Presets" and you should be able to figure out exactly where all your Lightroom presets are stored on each computer. If you edit one of these configuration files, just make sure you copy it to any other computer where you plan to use it again. For example, I only do imports from flash cards on two of my computers, so those two are the only ones where I bother copying those particular configuration files.
My main working Lightroom catalog is stored on that external drive. Seth Resnick suggests leaving the catalog with whatever name Lightroom creates by default. I changed mine to my own copyright name so that I could see exactly where it was at all times. I keep all of that catalog's images on that same drive too, more or less by the directory structure Seth recommends in the videos.
Now every computer will have its own program behaviour preferences for Lightroom (totally independent of the configuration files for things like copyright presets, develop presets, etc.). One of those program preferences is automated catalog backups. By default, Lightroom wants to back up the catalog once a week on opening. I just let it do that on each computer when asked, so there are mutliple backups of my catalog all over the place. I also have one of my PCs set to automatically backup that entire external drive once a week (the PC where I leave the drive connected on most weekends). So the images themselves get backed up frequently too.
Once you open that catalog on a computer, and subsequently close Lightroom while working in that catalog, Lightroom will try to open that same catalog the next time you start it. So you only have to point Lightroom to your external drive one time on each computer.
You'll have to decide whether to keep all your metadata just in the Lightroom catalog, or stored in individual XMP sidecar files for each image. There's a good discussion of that in the videos. Personally, I can understand arguments on both sides. I decided to go with the sidecars because I hit the same images with several different programs that can all interpret the sidecar files. If I only used Lightroom and Photoshop, I might not do that. If you decide not to use sidecars, you'll have to be very careful about backing up your catalog, because that's where everything you do in Lightroom will get saved. Again, the discussion in the videos is very clear.
I'm probably forgetting something important. If I remember anything else, I'll add it here.
