Oh, and I forgot to mention.. although that is a rather large sampling of data used in the analysis, you have to remember the failure curve on drives is very dramatic at a given age. For a proper test, average age won’t work. All drives need to be spun up at the beginning at the same time for accurate MTBF data. The average age isn’t quite as accurate as you would think because of the dramatic reliability curve dropoff and a given age (varies by drive a LOT). The failure curve is so far from flat, that average age isn’t all that useful for this purpose.
Thanks for your comments on the Seagate Constellation series. It seems one must buy the retail package/version of these hard drives to get the five year warranty direct from Seagate. I would buy one today if I needed one.