Seems that I only learn about electronics when I break or create catastrophic errors and I have had quite a bit of experience with hard drives. Perhaps I can save others from the frustration of making the same errors that I have made with hard drives...
Here's some tips to prevent hard drive problems . I am currently using the Western Digital My Book Studio Drive, the one with all the permanently installed hardware on it for backing up. Apparently if one is clever enough there is an update procedure for the firmware that removes the offending software, but It doesn't bother me.
Don't even think about getting a USB only Toaster drive for your Mac because of the wide availability and inexpensive price. The transfer speeds are ridiculously slow. Get fire wire 800 with 400 and likely E-sata to boot and pray that Apple or at least OWC keep offering an E-sata Mod on some of the new Imacs.
The OWC Hard Drive Toaster, called the "VOYAGER" can play another bare hard drive faster than you can say "remove the jumper". That is, make sure and remove the adjustable jumper on the rear of the hard drive if any. I had a heck of a time to get any hard drives to mount from any of the several HD Docks, until I removed those jumpers!
Cooling: I am a cooling nut and although fans are noisy I just don't trust hard drives that are not actively cooled over the long term. Sure modern components can handle a lot of heat, but at what cost A good heat sink is OK too. Extreme Heating and cooling cycles tend to stress electronic circuitry and cause weak parts or poor solders to fail more quickly, when it's easier to get a warranty replacement. I always try to heat stress any new electronics by alternatively leaving them on and then turning of for a quick cool down and then back up again for a prolonged heat cycle.
As fond as I am of the OWC Voyager bare drive "toaster", I am just as unhappy with the REFURBISHED MERCURY PRO DUAL DRIVES. I bought three refurbs thinking that they had faults that now a human has repaired so they will be more reliable than a new drive. Well, 2 of the 3 dual drives failed within about 90 days and I just managed to not lose my 1 TB itunes library. Another setting I would not recommend the JBOD or concantnated discs if there is no way to recover the good drive if one of the pair should fail. If one of the hard drives in the pair fails then the other drive is lost without it, which really puts all of the data at risk if only one drive fails. Seems strange, but I couldn't find an easy way to extract my data from the one good drive when it was impossible to re -pair the second hard drive in the box. AS 2 TB HD came down in price I merely got a single 2 TB drive, so I could sxtore all my itunes files on one drive.
Upon later investigation pair of 1 TB WD drives I bought may not have been the best choice for RAID pairing. Western Digital makes some drives that are made for Matched RAID configurations and some drives that are not designated, and this little fact may require some deeper digging into the documentation before purchase. use drives which should not be used as pairs and some made just for RAID pairing.
However, I did send in one of the Mercury Elite Pro Aluminum dual drive cases back for repair, when trouble shooting appeared to indicate a bad controller, but only other cheaper parts were replaced but not the controller. The drive worked for about 5 minutes and then stopped. I have made some changes to my views of refurbs after having several refurbished products die very quickly. I believe refurbs are just patched so they can get sent out the door without repairing deeper problems within a unit and the onus is on the new owner to return the defective products. Bottom line, it appears companies can move out otherwise dead merchandise, move out flawed items and chances are that products will not come back, even if they break quickly, because many people are too busy.
I keep the Voyager (AKA Hard drive Toaster) with mounted 1TB WD Black Label bare HD on my desk hooked by FW800, in front of a large air cleaner fan with the large fan moving at reduced speeds, especially when the ambient room temperature gets very hot. There are some good temperature monitoring applications to play with. "Temperature monitor" seems to work ok. Wish i had some other internal temps to compare my results to?