High Failure Rate of Large Drives?

You probably got a bad batch. I am nervous about deploying arrays built from disks from the same batch for that reason -- they are likely to have a similar life-span, which makes getting replacements potentially very exciting when one fails.

It isn't impossible that there is some design defect with the drives, that's definitely happened before; however usually the Internet is full of complaints about the drive if there is really something wrong with it, as opposed to the usual background noise that you'll find about anything.

This is a hard question to answer unless you have the resources of a large organization. See Google's research into hard disk failures.

When doing a significant purchase of disks, I will determine the rough disk size with the lowest cost per byte, which is generally one generation older than the latest. This makes sense that they will improved that generation's reliability.

More platters + more heads equals higher chance of failure.

Take two common WD hard drives

640GB = two platters
1TB = three platters

    WD Black 640GB vs 1TB comparison

Drive Ready Time 11 sec  13
R/W Power watts  8.3     8.4
Idle Power watts 7.7     7.8
Standby watts    1       1
Max shock        300g    250g
Performance seek 29      33
Quiet seek       26      29

That extra platter = more noise, more power usage, more heat, slower drive ready time, more susceptible to shock damage, and more vibration.

If they made the same drive design with only one platter it would have even better specs. In this case these are consumer grade drives but they are high end consumer grade drives with double the cache and a 5 year warranty. You'll see similar math if you closely inspect the documentation on any brand or style of traditional hard drive (spinning platters). It's purely a matter of physics that more platters makes a drive less reliable.

Jeff Hengesbach was also right when he said

The primary concern with 'big' drives is the rebuild time when a failure occurs. The larger the drive, the longer the rebuild, the larger the window for additional drive failure and potential loss of the array. With "big" drives the business value of availability should determine a level of acceptable risk(array loss) which will drive your RAID level selection and drive count(More drives = more chances of drive failure).

add in some small dose of Graeme Perrow

A drive with fifty million sectors has ten times the chance of having a bad sector than a drive with five million sectors. I'm assuming the failure rate among large drives and small drives is the same here, which is probably not a good assumption

More platters = bad
More storage space is a mixed bag. Pros and Cons on that are numerous.
More sectors really is more chance for errors. Not necessarily linear in scale but definitely a factor.

Unless you need space more than reliability I would suggest sticking to single platter or dual platter drives. It takes research and in some cases luck to know what you'll get when ordering drives as some manufacturers not only avoid publishing the number of platters they may actually sell more than one drive under the same part number.

Take for example the WD3200AAKS there is a single platter 320GB version and a dual platter 320GB version (160GB x 2). On top of that there are multiple lables and drive housings being used so you can't easily look at the drive and know which platter is inside. The only way to know is to search online to know that WD3200AAKS-00B3A0 and WD3200AAKS-75VYA0 tell you which is single platter but no retailer will tell you which you'll get.

I believe a higher than normal failure rate is indicative of any new technology. I've always been told never to buy the first model year of a car, wait until they work the bugs out. I'd say the same thing probably holds true for many other things, including hard drives.