External drive for main library

Question

I'm reading about external drives to find one to hold main Lightroom library. I want to be able to import and develop photos from either of 2 workstations: MacPro with 2 2.66GHz dual core Intel Xeon and iMac with 2.33 GHz Intel core 2 duo. I have other externals on each workstation for Library backups. And original nefs and dngs, master copy psds, and print ready tiifs are all burned to CDs or DVDs.
Drive wouldn't need to be bus powered, but I can't find any with a second power adapter available. Doesn't need to be smaller than a paperback. Don't know enough about Raid or SATA drives yet, except that some photographers use them for this purpose. Main concern for me is that editing speed be close to what it is now on the internal drives.
Will a Firewire 400 external at 72,000 rpm be close to same speed or is SATA faster and as reliable?
Thank you.

Answer 1

SATA is marginally faster. You have to determine where the bottlenecks are. For example, on my 1.8GHz Centrino notebook, running Lightroom, with my catalog database file on the notebook's drive, but the actual image files on a network hard drive (Gigabit network; 1000BaseT), it takes a second or two for a 12MB RAW (DNG) file to find its way from the network drive to my notebook, but many seconds for Lightroom to process it (for example, loading it into the Develop module, or performing the calculations for an export to local drive).
An export to local drive can take ten seconds per 15Megapixel image. That's about 1.5 seconds of IO time reading from the network drive, and about 1 second write time to the local drive. That means there are 7.5 seconds spent in reading the database file, applying corrections, rendering the image in its export format, and other associated calculations.
So I'm 25% IO bound, and 75% computationally bound (processor speed and RAM speed).
This being the case, even if I doubled my network drive's performance, I would only improve my overall performance by 12.5%. If I doubled my computational power, I would improve my total performance by 37.5%.
You may find that you are IO bound to a more significant degree. But even then, you're unlikely to notice an appreciable real world difference between Firewire400, USB2.0, and Gigabit networking. Yes, there are differences, but in the grand scheme of things, the difference between them in real world total throughput is not enough to make a huge difference to your Lightroom performance.