Yeah, you are right too many of my questions are too general but I guess even I narrowed it down to "are Hitachi/IBM drives made today better than Hitachi/IBM drives made 4 years ago" it would be difficult to answer but nevertheless an answer I would love to know.
This also runs in to the problem of what does "better" mean and while there are many measure I guess I would be happy with less failures/1000. (happy until I get that number and then I would want something else.....)
The mention of MTBF (or AFR) is interesting because some will claim that it is a false number and has not real decision making value. I would love to see defect numbers versus stated MTBF versus manufacturer to see who is embellishing more than others.
Yeah, SAS etc are connects but they will also generally define the class of drive (I don't think I seen too many Enterprise PATA drives). In specific cases that we face today, if we but a SAS drive chassis we can populate with high cost SAS drives or lower cost SATA's. If the SAS's are truly more reliable (less failures/1000) perhaps the higher cost would be justified.
The bathtub curve is one that is interesting and the more I think about it I think that it really is a composite curve where firmware problems would ONLY show up close to t=0 and mechanical wear at t+x where x would tend to vary from mfg to mfg. If so, with proper data, we should be able to see which mfg does a better job with various components of the drive (firmware testing, mechanical stability, etc etc )